Rigid polymeric beverage bottles with improved resistance to permeant elution

ABSTRACT

Carbonated beverages can have a substantially reduced concentration of water soluble materials derived from biaxially oriented thermoformed beverage containers. Such containers can comprise a permeant barrier and an active trap for water soluble materials that can be removed from the thermoplastic by extraction into the carbonated beverage. The improved container material comprises a blow molded thermoplastic polyester web comprising a compatible modified cyclodextrin material having pendent moieties or substituents that render the cyclodextrin material compatible with the container thermoplastic. The cyclodextrin material, after it is added to the polymer material, acts as a barrier and to trap extractable materials as they permeate through the thermoplastic polyester. The cyclodextrin molecule has a large center cavity having properties that increase the likelihood that organic molecules will be absorbed and trapped in the center pore. The resulting polyester is substantially resistant to any extraction of soluble materials from the polyester material by the carbonated beverage.

This application is a division of Ser. No. 09/549,481, filed Apr. 14,2000, now U.S. Pat. No. 6,306,936, which is a division of Ser. No.09/189,217, filed Nov. 10, 1998, now U.S. Pat. No. 6,136,354, which is adivision of Ser. No. 08/931,324, filed Sep. 16, 1997, now U.S. Pat. No.5,837,339, which is a CIP of Ser. No. 08/264,771, filed Jun. 23, 1994,now U.S. Pat. No. 5,492,947, which applications are incorporated hereinby reference.

FIELD OF THE INVENTION

The invention relates to a beverage bottle comprising a rigidthermoplastic monolayer, bilayer or multilayer container having in atleast one layer an amount of a substituted or modified cyclodextrin thatprevents the passage of a permeant, or the elution of a soluble materialfrom the thermoplastic into the liquid container contents. The inventionalso relates to biaxially oriented thermoformed polyolefin or polyesterthermoplastic beverage containers resistant to the movement or passageof a permeant into the beverage and resistant to the extraction orelution of beverage soluble materials from the polyester web into thebeverage.

BACKGROUND OF THE INVENTION

Rigid, or semirigid, thermoplastic beverage containers have been knownfor many years. One example of such containers are high densitypolyethylene milk containers that have a capacity of a quart, a gallonor other common sizes. These containers typically comprise high densitypolyethylene. High density polyethylene is made from an ethylene streamusing a Ziegler-Natta catalyst in either liquid phase or gas phaseprocesses. Other vinyl polymers can also be used in formulating thesebeverage containers including polymers made from such monomers includingethylene, propylene, butylene, butadiene, styrene and others. Suchmaterials often contain small concentrations of residual monomers,contaminants in the olefin feed, catalyst residues and othercontaminants. Such containers are typically blow molded using commonthermoforming technology to shape a preform into a finished bottle orcontainer.

Biaxially oriented blow molded thermoformed polyester beveragecontainers are disclosed in J. Agranoff (Ed) Modern Plastics,Encyclopedia, Vol. 16, No. 10A, P. (84) pp. 192-194. These beveragecontainers are typically made from a polyester material. Such polyestersare commonly made from a diol such as ethylene glycol, 1,4-butane diol,1,4-cyclohexane diol and other diols copolymerized with an organicdiacid compound or lower diester thereof such as terephthalic acid,2,6-naphthalene dicarboxylic acid etc. The condensation/polymerizationreaction occurs between the dicarboxylic acid, or a dimethyl esterthereof and the glycol material in a heat driven reaction that releaseswater or methanol as a reaction by-product leaving the high molecularweight polyester material. Typically, bulk polyester is injection blowmolded over a steel-core rod or are formed into a preform containing thepolyester. The preform is introduced into a blow molding machine whereinthe polyester is heated and blown to an appropriate shape and volume fora beverage container the preform can be a single layer material, can bea bilayer or multilayer preform. Such preforms can form bilayer ormultilayer bottles.

The thermoplastic polyester is a high molecular weight material, but cancontain a large variety of relatively low molecular weight compound,substantially less than 500 grams per mole. These compounds can beextractable into beverage within the container. These beverageextractable materials typically comprise impurities in feed streams ofthe diol or diacid used in making the polyester. Further, theextractable materials can comprise degradation by-products of thepolymerization reaction, the preform molding process or thethermoforming blow molding process. Further, the extractable materialscan contain residual diester, diol or diacid materials includingmethanol, ethylene glycol, terephthalic acid, dimethyl terephthalic,2,6-naphthalene dicarboxylic acid and esters or ethers thereof.Relatively low molecular weight oligomeric linear or cyclic diesters,triesters or higher esters made by reacting one mole of ethylene glycolwith one mole of terephthalic acid may be present. These relatively lowmolecular oligomers can comprise two or more moles of diol combined withtwo or more moles of diacid. Schiono, Journal of Polymer Science:Polymer Chemistry Edition, Vol. 17, pp. 4123-4127 (1979), John Wiley &Sons, Inc. discusses the separation and identification of PET impuritiescomprising poly(ethylene terephthalate) oligomers by gel permeationchromatography. Bartl et al., “Supercritical Fluid Extraction andChromatography for the Determination of Oligomers and Poly(ethyleneterephthalate) Films”, Analytical Chemistry, Vol. 63, No. 20, Oct. 15,1991, pp. 2371-2377, discusses experimental supercritical fluidprocedures for separation and identification of a lower oligomerimpurity from polyethylene terephthalate films.

Beverages containing these soluble/extractables, when consumed by thepublic, can exhibit an off-taste, a changed taste or even, in somecases, reduced taste due to the presence of extractable compounds. Theextractable compounds can add to or interfere with the perception ofeither the aroma note or flavor notes from the beverage material.Additionally, some substantial concern exists with respect to thetoxicity or carcinogenicity of any organic material that can beextracted into beverages for human consumption.

The technology relating to compositions used in the manufacture ofbeverage containers is rich and varied. In large part, the technology isrelated to coated and uncoated polyolefin containers and to coated anduncoated polyester that reduce the permeability of gasses such as carbondioxide increasing shelf life. The art also relates to manufacturingmethods and to bottle shape and bottom configuration. Deaf et al., U.S.Pat. No. 5,330,808 teach the addition of a fluoroelastomer to apolyolefin bottle to introduce a glossy surface onto the bottle. Visioliet al., U.S. Pat. No. 5,350,788 teach methods for reducing odors inrecycled plastics. Visioli et al. disclose the use of nitrogen compoundsincluding polyalkylenimine and polyethylenimine to act as odorscavengers in polyethylene materials containing a large proportion ofrecycled polymer.

Wyeth et al., U.S. Pat. No. 3,733,309 show a blow molding machine thatforms a layer of polyester that is blown in a blow mold. Addleman, U.S.Pat. No. 4,127,633 teaches polyethylene terephthalate preforms which areheated and coated with a polyvinylidene chloride copolymer latex thatforms a vapor or gas barrier. Halek et al., U.S. Pat. No. 4,223,128teaches a process for preparing polyethylene terephthalate polymersuseful in beverage containers. Bonnebat et al., U.S. Pat. No. 4,385,089teaches a process for preparing biaxially oriented hollow thermoplasticshaped articles in bottles using a biaxial draw and blow moldingtechnique. A preform is blow molded and then maintained in contact withhot walls of a mold to at least partially reduce internal residualstresses in the preform. The preform can be cooled and then blown to theproper size in a second blow molding operation. Gartland et al., U.S.Pat. No. 4,463,121 teaches a polyethylene terephthalate polyolefin alloyhaving increased impact resistance, high temperature, dimensionalstability and improved mold release. Ryder, U.S. Pat. No. 4,473,515teaches an improved injection blow molding apparatus and method. In themethod, a parison or preform is formed on a cooled rod from hotthermoplastic material. The preform is cooled and then transformed to ablow molding position. The parison is then stretched, biaxally oriented,cooled and removed from the device. Nilsson, U.S. Pat. No. 4,381,277teaches a method for manufacturing a thermoplastic container comprisinga laminated thermoplastic film from a preform. The preform has athermoplastic layer and a barrier layer which is sufficientlytransformed from a preformed shape and formed to a container. Jakobsenet al., U.S. Pat. No. 4,374,878 teaches a tubular preform used toproduce a container. The preform is converted into a bottle. Motill,U.S. Pat. No. 4,368,825; Howard Jr., U.S. Pat. No. 4,850,494; Chang,U.S. Pat. No. 4,342,398; Beck, U.S. Pat. No. 4,780,257; Krishnakumar etal., U.S. Pat. No. 4,334,627; Snyder et al., U.S. Pat. No. 4,318,489;and Krishnakumar et al., U.S. Pat. No. 4,108,324 each teach plasticcontainers or bottles having preferred shapes or self-supporting bottomconfigurations. Hirata, U.S. Pat. No. 4,370,368 teaches a plastic bottlecomprising a thermoplastic comprising vinylidene chloride and an acrylicmonomer and other vinyl monomers to obtain improved oxygen, moisture orwater vapor barrier properties. The bottle can be made by casting anaqueous latex in a bottle mold, drying the cast latex or coating apreform with the aqueous latex prior to bottle formation. Kuhfuss etal., U.S. Pat. No. 4,459,400 teaches a poly(ester-amid) compositionuseful in a variety of applications including packaging materials.Maruhashi et al., U.S. Pat. No. 4,393,106 teaches laminated or plasticcontainers and methods for manufacturing the container. The laminatecomprises a moldable plastic material in a coating layer. Smith et al.,U.S. Pat. No. 4,482,586 teaches a multilayer of polyester article havinggood oxygen and carbon dioxide barrier properties containing apolyisophthalate polymer. Walles, U.S. Pat. Nos. 3,740,258 and 4,615,914teaches that plastic containers can be treated, to improve barrierproperties to the passage of organic materials and gases such as oxygen,by sulfonation of the plastic.

Further, we are aware that the polyester has been developed andformulated to have high burst resistance to resist pressure exerted onthe walls of the container by carbonated beverages. Further, somesubstantial work has been done to improve the resistance of thepolyester material to stress cracking during manufacturing, filling andstorage.

Beverage manufacturers have long searched for improved barrier material.In larger part, this research effort was directed to carbon dioxide(CO₂) barriers, oxygen (O₂) barriers and water vapor (H₂O) barriers.More recently original bottle manufacturers have had a significantincrease in sensitivity to the presence of beverage extractable orbeverage soluble materials in the resin or container. This work has beento improve the bulk plastic with polymer coatings or polymer laminatesof less permeable polymer to decrease permeability. However, we areunaware of any attempt at introducing into bulk polymer resin orpolyester material of a beverage container, an active complexingcompound to improve barrier properties or to trap water soluble materialto prevent their extraction or elution into the carbonated beverage.

Even with this substantial body of technology, substantial need hasarisen to develop biaxially oriented thermoplastic polymer materials forbeverage containers that can substantially reduce the passage ofpermeants in the extractable materials that pass into beverages intendedfor human consumption.

BRIEF DISCUSSION OF THE INVENTION

I have found that the barrier or trapping properties of polymericbeverage bottles preferably polyolefin or polyester biaxially orientedpolymeric beverage container can be improved. Specifically, theresistance to extraction of soluble materials from the bulk polymer intothe beverage, can be improved, without any important reduction andclarity, processability or structural properties, through the use of amodified cyclodextrin or compatible cyclodextrin derivative incorporatedinto or coated on the beverage container polymer material. We have foundthat the cyclodextrin material can increase the barrier properties ofthe polymer material by trapping permeants in an internal hydrophobicspace in the cyclodextrin molecule. Further, any small molecule oroligomer impurity present in the container thermoplastic, that can beextracted by the beverage, can also be trapped in the cyclodextrinbefore the impurity material can migrate to the beverage.

In this technology, the cyclodextrin material can be incorporated,dispersed or suspended in the bulk polymer used to make the plasticbottle, the cyclodextrin can be incorporated, suspended or dispersed ina second thermoplastic layer than can be coextruded with thethermoplastic material forming the bottle. Lastly, the cyclodextrinmaterial can be used in an aqueous or solvent based liquid coatingmaterial that can be added to the bottle in the preform stage or in thefully formed bottle stage. Preferred containers comprise a high densitypolyethylene milk container and a PET/polyacrylonitrile bilayer bottleor container.

Preferably the cyclodextrin material is used in the form of a compatiblederivatized cyclodextrin. The cyclodextrin molecule without a compatiblesubstituent often is not sufficiently compatible in the bulk polymermaterial to result in a clear, useful trapping or barrier layer in thepackaging material. The compatible cyclodextrin derivative is a compoundsubstantially free of an inclusion complex. For this invention, the term“substantially free of an inclusion complex” means that the quantity ofthe dispersed cyclodextrin material in the bulk polymer contains a largefraction having cyclodextrin free of a polymer contaminant, a permeantor other inclusion compound in the interior of the cyclodextrinmolecule. A cyclodextrin compound is typically added and blended in thebulk polymer without any inclusion compound but some complexing canoccur during manufacture. Such complexing can occur as polymerimpurities and degradation materials become the inclusion compound in acyclodextrin inclusion complex.

The preferred cyclodextrin is a derivatized cyclodextrin having at leastone substituent group bonded to the cyclodextrin molecule that iscompatible with the bulk polymer. Cyclodextrin is a cyclic dextrinmolecule having six or more glucose moieties in the molecule.Preferably, the cyclodextrin is an alpha cyclodextrin (α-CD), a betacyclodextrin (β-CD), and delta cyclodextrin (δ-CD) or mixtures thereof.We have found that the derivatization of the cyclodextrin moleculeresults in improved blending into the thermoplastic bulk polymer with noloss in clarity, processability, or structural or packaging property inthe bulk polymer. The substituents on the cyclodextrin molecule areselected to possess a composition, structure and polarity to match thatof the polymer to ensure the cyclodextrin is sufficiently compatible inthe polymer material. Further, I have found that derivatizedcyclodextrin can be blended into thermoplastic polymer, formed intosemirigid or rigid containers of the invention using conventionalthermoplastic blow molding/thermoforming manufacturing techniques.Lastly, we have found that the cyclodextrin material used in a varietyof aspects of the invention, can be used in forming such thermoplasticbeverage containers without any substantial reduction in structuralproperties.

The first aspect of the invention comprises a thermoplastic polymerpellet having a major proportion of the thermoplastic beverage polyestermaterial having a sufficient amount of the cyclodextrin material toimprove barrier properties and to serve as a trap for polymerimpurities. A second aspect of the invention comprises a thermoplasticbeverage container comprising a thermoplastic polyester having a majorproportion of the polymeric material and a minor but effective amount ofthe cyclodextrin material to improve barrier properties and to act as atrap for polymer impurities. The third aspect of the invention comprisesa beverage container comprising a major proportion of a structuralthermoplastic polymer having a second laminate layer comprising athermoplastic layer comprising a thermoplastic polymer and an effectiveamount of a cyclodextrin material to improve barrier properties to thebeverage container and to act as a trap for polymer purities in thelaminate structure of the beverage container. A last aspect of theinvention comprises a beverage container comprising a thermoplasticstructure having an internal coating comprising a film forming materialhaving an effective amount of a cyclodextrin material that can provideand improve barrier properties or act as a trap for the impurities inthe beverage container.

BRIEF DISCUSSION OF THE DRAWING

FIG. 1 is a graphical representation of the dimensions of thecyclodextrin molecule without derivatization. The central pore comprisesthe hydrophilic space or volume within the cyclodextrin molecule thatcan be the site for absorption of a permeant or contaminant. The alpha,beta and gamma cyclodextrins are shown.

FIG. 2 is an isometric view of a two liter polyester bottle having asecond layer on the thermoplastic comprising a polymer and an effectiveamount of cyclodextrin derivative.

DETAILED DISCUSSION OF THE INVENTION

We have found that useful engineering thermoplastic polymer resins canbe improved for applications involving packaging beverages. We havefound that a modified cyclodextrin material with the polymer obtains hasimproved barrier properties and a reduced tendency to release polymerresidue by extraction into the bulk beverage liquid. The polyestermaterial useful in common engineering plastics of the invention is acondensation/polymerization product of a diacid and a polyol. Theproduct preferably employs an aromatic compound diacid such as aphthalate or naphthalate. The major diacids used in the polymers of theinvention are terephthalic acid (1,4-benzyene dicarboxylic acid) or2,6-naphthalene dicarboxylic acid. However, other phthalic acids andnaphthalene dicarboxylic acids can be used such as orthophthalic acid,1,7-naphthalene dicarboxylic acid etc. Polyesters are typically referredto as aromatic-aliphatic or aromatic according to the copolymerizeddiol. Thus, polyethylene terephthalate chemical abstract No. 25038-59-9(PET), poly (butylene terephthalate) chemical abstract No. 24968-12-5(PBT) and related polymers are termed aromatic-aliphatic polyesters.Poly(bisphenol A-phthalate) is called an aromatic polyester resin or apolyarlate resin. PET, PBT and poly (ethylene-2,6-naphthalenedicarboxylate resins) (PEN) are the largest volume aromatic aliphaticproducts. Other aromatic aliphatic products include Eastman Kodak'sKodar® resin which is a PET resin modified with isophalate and dimethylcyclohexane. Polyarlate resins are a lower volume special resins forhigh temperature (HDT) end uses. A preferred polyethylene terephthalicresin is typically made by a transesterification reaction of dimethylterephthalate with ethylene glycol or 1,4-butane diol in the presence ofa trace amount of a metal ion catalyst.

The methanol byproduct from the transesterification is collectedoverhead and the neat resin is extruded from the reactor in a batch ofcontinuous process. The product PET resin has an intrinsic viscosity (η)that ranges from about 0.72-0.85 dL/g. Often bottle grade PET resin,during manufacture, is heated under inert ambient atmosphere to promotefurther polymerization in the resin.

Polyester bottles are typically produced by injection blow molding. Twomanufacturing techniques are typically used. In one method, a preform ismade by injection mold techniques in a preformed shape having the neckand screw-cap portion of the bottle in approximately useful size buthaving the body of the preform substantially smaller than the finalbottle shape. A single component or bilayer preform can be used. Thepreform is then inserted into a blow molding machine where it is heatedand then blown into the appropriate shape. Alternatively, the resin canbe injection below molded over a steel-core rod. The neck of the bottleis formed with the proper shaped received closures (cap) and resin isprovided around the temperature conditioned rod for the blowing step.The rod with the resin is indexed into the molding and the resin isblown away from the rod against the mold walls. The resin cools incontact with the mold while into the transparent bottle. The finishedbottle is ejected and the rod is moved again in the injection moldingstation. This process is favored for single cylindrical bottles buttypically can not be used to introduce complex shapes such as handlesinto a bottle.

The most common machine involves a four station apparatus that caninject resin, blow the resin into the appropriate shape, strip theformed container from the rod and recondition the core rod prior to therepeat of the process. Such containers are typically manufactured withthe closure fitment portion comprising a threaded neck adapted to ametal screw cap. The bottle bottom typically has a lobed design such asa four lobe or five lobe design to permit the bottle be placed in astable upright position. Alternatively, the molded bottles, having ahemispherical bottom, can be adhesively bonded to a polyethylene orpolypropylene base cut to provide placement stability.

Cyclodextrin

The thermoplastic films of the invention contain a modified substitutedor derivatized cyclodextrin having pendent moieties or substituents thatrender the cyclodextrin material compatible with the thermoplasticpolyester polymer. For this invention, compatible means that thecyclodextrin material can be uniformly dispersed into the melt polymer,can retain the ability to trap or complex permeant materials or polymerimpurity, and can reside in the polymer without substantial reductionsin polymer film barrier properties or container forming characteristics.Compatibility can be determined by measuring polymer characteristicssuch as tensile strength, tear resistance, etc., permeability ortransmission rates for permeants, surface smoothness, clarity, etc.Qualitative compatibility screening can be obtained by preparing smallbatches (100 grams-one kilogram of thermoplastic and substitutedcyclodextrin). The blended material is extruded at productiontemperatures as a linear strand extrudate having a diameter of about oneto five mm. Incompatible cyclodextrin materials will not disperseuniformly in the melt and can be seen in the transparent melt polymerimmediately upon extrusion from the extrusion head. We have found theincompatible cyclodextrin can degrade at extrusion temperatures andproduce a characteristic “burnt flour” odor in an extrusion. Further, wehave found that incompatible cyclodextrin can cause substantial meltfracture in the extrudate which can be detected by visual inspection.Lastly, the extrudate can be cut into small pieces, cross-sectioned andexamined using an optical microscope to find incompatible cyclodextrinclearly visible in the thermoplastic matrix.

Cyclodextrin is a cyclic oligosaccharide consisting of at least five,preferably six glucopyranose units joined by α(1→4) linkages. Althoughcyclodextrin with up to twelve glucose residues are known, the threemost common homologs (αcyclodextrin, βcyclodextrin and γcyclodextrin)having 6, 7 and 8 residues have been used.

Cyclodextrin is produced by a highly selective enzymatic synthesis. Theycommonly consist of six, seven, or eight glucose monomers arranged in adonut shaped ring, which are denoted α, β, or γ cyclodextrinrespectively (See FIG. 1). The specific coupling of the glucose monomersgives the cyclodextrin a rigid, truncated conical molecular structurewith a hollow interior of a specific volume. This internal cavity, whichis lipophilic (i.e.,) is attractive to hydrocarbon materials (in aqueoussystems is hydrophobic) when compared to the exterior, is a keystructural feature of the cyclodextrin, providing the ability to complexmolecules (e.g., aromatics, alcohols, halides and hydrogen halides,carboxylic acids and their esters, etc.). The complexed molecule mustsatisfy the size criterion of fitting at least partially into thecyclodextrin internal cavity, resulting in an inclusion complex.

CYCLODEXTRIN (CD) TYPICAL PROPERTIES

PROPERTIES α-CD β-CD γ-CD Degree of 6 7 8 Polymerization (n = )Molecular Size (Å) inside diameter 5.7 7.8 9.5 outside diameter 13.715.3 16.9 height 7.0 7.0 7.0 Specific Rotation [α]²⁵ _(D) +150.5 +162.5+177.4 Color of iodine Blue Yellow Yellowish complex Brown Solubility inwater (g/100 ml) 25° C. Distilled Water 14.50 1.85 23.20

The oligosaccharide ring forms a torus, as a truncated cone, withprimary hydroxyl groups of each glucose residue lying on a narrow end ofthe torus. The secondary glucopyranose hydroxyl groups are located onthe wide end. The torus interior is hydrophobic due to the presence ofmethylene (—CH₂—) and ether (—O—) groups. The parent cyclodextrinmolecule, and useful derivatives, can be represented by the followingformula (the ring carbons show conventional numbering) in which thevacant bonds represent the balance of the cyclic molecule:

wherein R₁ and R₂ are primary or secondary hydroxyl respectively asshown.

Cyclodextrin molecules have available for reaction with a chemicalreagent the primary hydroxyl at the six position, of the glucose moiety,and at the secondary hydroxyl in the two and three position. Because ofthe geometry of the cyclodextrin molecule, and the chemistry of the ringsubstituents, all hydroxyl groups are not equal in reactivity. However,with care and effective reaction conditions, the cyclodextrin moleculecan be reacted to obtain a derivatized molecule having all hydroxylgroups derivatized with a single substituent type. Such a derivative isa persubstituted cyclodextrin. Cyclodextrin with selected substituents(i.e.) substituted only on the primary hydroxyl or selectivelysubstituted only at one or both the secondary hydroxyl groups can alsobe synthesized if desired. Further directed synthesis of a derivatizedmolecule with two different substituents or three different substituentsis also possible. These substituents can be placed at random or directedto a specific hydroxyl. For the purposes of this invention, thecyclodextrin molecule needs to contain sufficient thermoplasticcompatible substituent groups on the molecule to insure that thecyclodextrin material can be uniformly dispersed into the thermoplasticand when formed into a clear film, sheet or rigid structure, does notdetract from the polymer physical properties.

Apart from the introduction of substituent groups on the CD hydroxylother molecule modifications can be used. Other carbohydrate moleculescan be incorporated into the cyclic backbone of the cyclodextrinmolecule. The primary hydroxyl can be replaced using SN₂ displacement,oxidized dialdehyde or acid groups can be formed for further reactionwith derivatizing groups, etc. The secondary hydroxyls can be reactedand removed leaving an unsaturated group to which can be added a varietyof known reagents that can add or cross a double bond to form aderivatized molecule. Further, one or more ring oxygen of the glycanmoiety can be opened to produce a reactive site. These techniques andothers can be used to introduce compatibilizing substituent groups onthe cyclodextrin molecule.

The preferred preparatory scheme for producing a derivatizedcyclodextrin material having a functional group compatible with thethermoplastic polymer involves reactions at the primary or secondaryhydroxyls of the cyclodextrin molecule. Broadly we have found that abroad range of pendant substituent moieties can be used on the molecule.These derivatized cyclodextrin molecules can include acylatedcyclodextrin, alkylated cyclodextrin, cyclodextrin esters such astosylates, mesylate and other related sulfo derivatives,hydrocarbyl-amino cyclodextrin, alkyl phosphono and alkyl phosphatocyclodextrin, imidazoyl substituted cyclodextrin, pyridine substitutedcyclodextrin, hydrocarbyl sulphur containing functional groupcyclodextrin, silicon-containing functional group substitutedcyclodextrin, carbonate and carbonate substituted cyclodextrin,carboxylic acid and related substituted cyclodextrin and others. Thesubstituent moiety must include a region that provides compatibility tothe derivatized material.

Acyl groups that can be used as compatibilizing functional groupsinclude acetyl, propionyl, butyryl, trifluoroacetyl, benzoyl, acryloyland other well known groups. The formation of such groups on either theprimary or secondary ring hydroxyls of the cyclodextrin molecule involvewell known reactions. The acylation reaction can be conducted using theappropriate acid anhydride, acid chloride, and well known syntheticprotocols. Peracylated cyclodextrin can be made. Further, cyclodextrinhaving less than all of available hydroxyls substituted with such groupscan be made with one or more of the balance of the available hydroxylssubstituted with other functional groups.

Cyclodextrin materials can also be reacted with alkylating agents toproduced an alkylated cyclodextrin. Alkylating groups can be used toproduce peralkylated cyclodextrin using sufficient reaction conditionsexhaustively react available hydroxyl groups with the alkylating agent.Further, depending on the alkylating agent, the cyclodextrin moleculeused in the reaction conditions, cyclodextrin substituted at less thanall of the available hydroxyls can be produced. Typical examples ofalkyl groups useful in forming the alkylated cyclodextrin includemethyl, propyl, benzyl, isopropyl, tertiary butyl, allyl, trityl,alkyl-benzyl and other common alkyl groups. Such alkyl groups can bemade using conventional preparatory methods, such as reacting thehydroxyl group under appropriate conditions with an alkyl halide, orwith an alkylating alkyl sulfate reactant.

Tosyl(4-methylbenzene sulfonyl) mesyl (methane sulfonyl) or otherrelated alkyl or aryl sulfonyl forming reagents can be used inmanufacturing compatibilized cyclodextrin molecules for use inthermoplastic resins. The primary —OH groups of the cyclodextrinmolecules are more readily reacted than the secondary groups. However,the molecule can be substituted on virtually any position to form usefulcompositions.

Such sulfonyl containing functional groups can be used to derivatizeeither of the secondary hydroxyl groups or the primary hydroxyl group ofany of the glucose moieties in the cyclodextrin molecule. The reactionscan be conducted using a sulfonyl chloride reactant that can effectivelyreact with either primary or secondary hydroxyl. The sulfonyl chlorideis used at appropriate mole ratios depending on the number of targethydroxyl groups in the molecule requiring substitution. Both symmetrical(per substituted compounds with a single sulfonyl moiety) orunsymmetrical (the primary and secondary hydroxyls substituted with amixture of groups including sulfonyl derivatives) can be prepared usingknown reaction conditions. Sulfonyl groups can be combined with acyl oralkyl groups generically as selected by the experimenter. Lastly,monosubstituted cyclodextrin can be made wherein a single glucose moietyin the ring contains between one and three sulfonyl substituents. Thebalance of the cyclodextrin molecule remaining unreacted.

Amino and other azido derivatives of cyclodextrin having pendentthermoplastic polymer containing moieties can be used in the sheet, filmor container of the invention. The sulfonyl derivatized cyclodextrinmolecule can be used to generate the amino derivative from the sulfonylgroup substituted cyclodextrin molecule via nucleophilic displacement ofthe sulfonate group by an azide (N₃ ⁻¹) ion. The azido derivatives aresubsequently converted into substituted amino compounds by reduction.Large numbers of these azido or amino cyclodextrin derivatives have beenmanufactured. Such derivatives can be manufactured in symmetricalsubstituted amine groups (those derivatives with two or more amino orazido groups symmetrically disposed on the cyclodextrin skeleton or as asymmetrically substituted amine or azide derivatized cyclodextrinmolecule. Due to the nucleophilic displacement reaction that producesthe nitrogen containing groups, the primary hydroxyl group at the6-carbon atom is the most likely site for introduction of a nitrogencontaining group. Examples of nitrogen containing groups that can beuseful in the invention include acetylamino groups (—NHAc), alkylaminoincluding methylamino, ethylamino, butylamino, isobutylamino,isopropylamino, hexylamino, and other alkylamino substituents. The aminoor alkylamino substituents can further be reactive with other compoundsthat react with the nitrogen atom to further derivatize the amine group.Other possible nitrogen containing substituents include dialkylaminosuch as dimethylamino, diethylamino, piperidino, piperizino, quaternarysubstituted alkyl or aryl ammonium chloride substituents, halogenderivatives of cyclodextrins can be manufactured as a feed stock for themanufacture of a cyclodextrin molecule substituted with acompatibilizing derivative. In such compounds the primary or secondaryhydroxyl groups are substituted with a halogen group such as fluoro,chloro, bromo, iodo or other substituents. The most likely position forhalogen substitution is the primary hydroxyl at the 6-position.

Hydrocarbyl substituted phosphono or hydrocarbyl substituted phosphatogroups can be used to introduce compatible derivatives onto thecyclodextrin. At the primary hydroxyl, the cyclodextrin molecule can besubstituted with alkyl phosphato, aryl phosphato groups. The 2, and 3,secondary hydroxyls can be branched using an alkyl phosphato group.

The cyclodextrin molecule can be substituted with heterocyclic nucleiincluding pendent imidazole groups, histidine, imidazole groups,pyridino and substituted pyridino groups.

Cyclodextrin derivatives can be modified with sulfur containingfunctional groups to introduce compatibilizing substituents onto thecyclodextrin. Apart from the sulfonyl acylating groups found above,sulfur containing groups manufactured based on sulfhydryl chemistry canbe used to derivatize cyclodextrin. Such sulfur containing groupsinclude methylthio (—SMe), propylthio (—SPr), t-butylthio (—S—C(CH₃)₃),hydroxyethylthio (—S—CH₂CH₂OH), imidazolylmethylthio, phenylthio,substituted phenylthio, aminoalkylthio and others. Based on the ether orthioether chemistry set forth above, cyclodextrin having substituentsending with a hydroxyl aldehyde ketone or carboxylic acid functionalitycan be prepared. Such groups include hydroxyethyl, 3-hydroxypropyl,methyloxylethyl and corresponding oxeme isomers, formyl methyl and itsoxeme isomers, carbylmethoxy (—O—CH₂—CO₂H), carbylmethoxymethyl ester(—O—CH₂CO₂—CH₃). Cyclodextrin with derivatives formed using siliconechemistry can contain compatibilizing functional groups.

Cyclodextrin derivatives with functional groups containing silicone canbe prepared. Silicone groups generally refer to groups with a singlesubstituted silicon atom or a repeating silicone-oxygen backbone withsubstituent groups. Typically, a significantly proportion of siliconeatoms in the silicone substituent bear hydrocarbyl (alkyl or aryl)substituents. Silicone substituted materials generally have increasedthermal and oxidative stability and chemical inertness. Further, thesilicone groups increase resistance to weathering, add dielectricstrength and improve surface tension. The molecular structure of thesilicone group can be varied because the silicone group can have asingle silicon atom or two to twenty silicon atoms in the siliconemoiety, can be linear or branched, have a large number of repeatingsilicone-oxygen groups and can be further substituted with a variety offunctional groups. For the purposes of this invention the simplesilicone containing substituent moieties are preferred includingtrimethylsilyl, mixed methyl-phenyl silyl groups, etc. We are aware thatcertain βCD and acetylated and hydroxy alkyl derivatives are availablefrom American Maize-Products Co., Corn Processing Division, Hammond,Ind.

The preferred cyclodextrin derivative containing polyester beveragecontainers of the invention are commonly made by incorporating themodified cyclodextrin into a polyolefin or polyester resin that is thenformed into a useful pellet. The pellet is then formed into a preformshape which is then converted into a biaxally oriented beveragecontainer. Two techniques are typically used in manufacturing thebottles. First, a machine is used that converts the resin pellet into apreform formed on a heated rod. After conditioning, the preform is blownusing the rod and in conjunction with the balance of the manufacturingequipment into the bottle. A second technique involves forming a preformfrom thermoplastic resin. Removing the resin from the preformmanufacturing site and transferring the preform to a blow moldingapparatus. The preform is then blown in biaxally oriented into a usefulcontainer shape. The container can be self-supporting with a lobedbottom or can be adhesively bonded to a polyethylene or polypropylenebase cup support. In an alternative embodiment, the finished beveragecontainer can be at least a two layer laminate material. The laminatecan contain in one layer a polyester material and in a second layer abarrier polymer. The derivatized cyclodextrin material can be in eitherlayer or in both layers. In a third embodiment, a beverage container cancomprise a biaxally oriented beverage container having a coating on theinterior of the bottle. The coating can be placed in the preform havingsufficient thickness to adequately cover the interior of the beveragecontainer after blowing. Alternatively, the coating can be formed on theinterior of the container after blow molding.

Raw material used in any of the thermoforming procedures is a pelletizedthermoplastic polyester or polyolefin. The product of thetransesterification reaction producing a thermoplastic polyester is inthe form of a melt. The melt can be easily reduced to a useful pellet orother small diameter flake or particulate. The flake or particulatepolyester can then be dried and blended with the derivatizedcyclodextrin material until uniform and then melt extruded underconditions that obtain a uniform dispersion or solution of the modifiedor derivatized cyclodextrin and polyester material. The resultingpolyester pellet is typically substantially clear, uniform and ofconventional dimensions. The pellet preferably contains about 0.01 toabout 10 wt-% of the modified cyclodextrin, preferably about 0.1 toabout 5 wt-% of the modified cyclodextrin and under certaincircumstances, the polyester can contain between 0.5 and 2 wt-% of thecyclodextrin material. The polyester pellet containing the modifiedcyclodextrin material then can be incorporated into the conventionalpreform or parison blow molding techniques. The products of thesetechniques contain similar proportions of materials.

Molecular orientation substantially improves the stiffness, ultimatetensile strength, yield strength, impact resistance, clarity andpermeation resistance of many thermoplastic materials.

Biaxially oriented PET plastic carbonated soft drink bottle which isproduced from polyethylene terephthalate using methods taught in Wyethet al., U.S. Pat. No. 3,733,309 issued May 15, 1973 and entitled“Biaxially Oriented Poly (Ethylene Terephthalate) Bottle.” The majorityof the biaxially oriented PET beverage bottles are presently beingproduced by the so-called two stage “reheat blow” method, using aseparate machine for each stage. In a first stage injection moldingmachine, PET parisons or preforms are first injection molded in a cooledmold, at melt temperatures of about 540° F., which is above the polymersmelting point, and then cooled down and removed from the injectionmolding machine for later use as feed stock to a separate second stagereheat-blow machine, where the biaxially oriented bottle is produced.Upon entering the reheat blow machine, the cold parisons, whose shaperesembles that of a test tube having a threaded bottle neck finish atits open ended top, are heated uniformly in an oven to its orientationtemperature, which for PET is about 190° F. to 200° F. (which is belowPET's melting point). The temperature conditioned parisons are thenplaced within cooled bottle blow molds which clamp the parisons by theirnecks upon closing off the blow molds. Metal pushrods are then insertedand pushed into the parisons through their open necks, and the parisons,whose initial lengths are shorter than that of the finished bottle, arestretched axially against the bottom of the blow molds to their finallengths, thereby effecting axial or longitudinal orientation. Radial orso-called “hoop direction” orientation is next achieved by introducingcompressed air inside the axially stretched parisons to expand themoutward and into contact with the cooled surfaces of the bottle blowmolds. After cooling sufficiently for subsequent handling, the blowmolds open and the biaxially oriented bottles are ejected from themachine. While this method is suitable for use with orientablethermoplastic, it requires a substantial capital investment in theinjection molding machine and the reheat blow machine and its associatedparison transfer equipment and heating ovens. Furthermore, aconsiderable amount of energy is consumed in reheating the cold parisonsin the oven, which adds to the cost of the finished oriented articles.

The reheating step can be avoided if a so-called in-line single stageinjection blow molding process were utilized to make biaxially orientedhollow articles using a single “hot parison” injection stretch-blowmolding machine. In the “hot parison” in-line method, the parison isformed by injection molding, cooled to orientation temperature, and thenstretched axially and blown radially to its final product shape, withoutever being allowed to cool to room temperature. A number of such in-line“hot parison” injection stretch blowing methods and apparatus have beendisclosed in the paten literature and as such constitute the prior art.

As set forth in A. J. Scalora, U.S. Pat. No. 3,470,282, a hotthermoplastic parison is first formed by injection molding thethermoplastic material, at a temperature above its melting point, over agenerally cylindrical core, called an inner sleeve, which is positionedin the female cavity of an injection mold. The parison is then cooled,while on the core and within the injection mold, by suitable coolingmeans located therein, down to a narrow temperature range, whichincludes the preferred orientation temperature of the material beingprocessed, said temperature range being relatively uniform and coveringall points across the thickness and at the surfaces of the parison, andsaid temperature range also being below the thermoplastic materialshomogenous melting temperature. The narrow temperature range for PETparisons would be about 190° F. to 200° F. After reaching its narroworientation temperature range, the uniformly cooled parison is thenremoved from the injection mold and transferred, while still on theinner core, to a blow mold having cooling means therein. While intransit, or after being positioned within the closed blow molds, theparison is stretched axially by the outward extension of a valve locatedwithin the inner core over which the parison had been previously molded.Next, the parison is inflated, while positioned within the blow molds,thus stretching the parison along a second axis or direction of axialstretching. Stretching the thermoplastic parison at its orientationtemperature, by longitudinal or axial extension of a valve within thecore rod, and by radial inflation, sometimes referred to as “hoopstretching,” yields a biaxially oriented hollow article.

The arrangement described above has the virtues of simplicity and energyconservation mentioned previously, but it cannot operate at the highproduction rates necessary for economical production. For example, theparison must first be brought to orientation temperature throughout itsentire thickness. If the metal surfaces of the core and injection moldcavity are maintained at temperatures at or slightly below theorientation temperature range of the thermoplastic to be processed, 190°F. to 200° F. for PET, the parison will eventually be cooled to anequilibrium temperature condition corresponding to the desiredorientation temperature range, across its thickness, wile it is still inthe injection mold. However, the rate of cooling of the parison withinthe injection mold will be extremely slow because of the smalltemperature differential between the parison, the core, and the moldsurfaces. Thus, the speed of operation of the apparatus will be limitedby the long injection molding cycle required. In contrast, if the coreand injection mold cavities are maintained at a much lower temperature,conventionally about 35° to 40° F. for PET, the rate of cooling will beincreased substantially, but an uneven temperature distribution will becreated across the thickness of the parison. Such rapid cooling of theparison, if accomplished within an economical and commercially feasiblecycle time, will result in surface temperatures of the parison which aresubstantially below the orientation temperature range of thethermoplastic being processed and will actually approach the temperatureof the core and the injection mold, while the middle or mid-point of theparison walls will be substantially above the desired orientationtemperature range. Therefore, satisfactory orientation will not beachieved during the stretching and blowing of parisons which have suchsubstantial mal-distributions of temperatures across their thickness,major portions of which lie outside the orientation temperature range ofthe thermoplastic being processed.

The cycle time limitations resulting from the slow parison orpreform-cooling inherent in Scalora's teaching are overcome to a certaindegree in other subsequently disclosed art. For example, in Valyi, U.S.Pat. Nos. 3,966,378 and 4,151,248.

In U.S. Pat. No. 3,966,378, a parison is formed on a first core in aninjection mold, cooled in the injection mold, transferred on said firstcore to a pre-blow mold and partially expanded against the innersurfaces of the pre-blow mold to a shape intermediate that of theparison and that of the finished article. Next, cooling is effected onthe first core in the pre-blow mold to a uniform temperature across itsthickness within the desired orientation temperature range of thethermoplastic being molded. The temperature conditioned parison is thentransferred to a second blow core and later transferred to a third moldwhere it is axially stretched and expanded in the third mold, which isthe final blow mold, to form a hollow biaxially oriented article.Separate parisons may be simultaneously injection molded, preblown, andcooled to orientation temperature, and finally stretch-blown, ifmultiple sets of cores and molds are utilized. Because the parison isnot conditioned to a uniform orientation temperature across itsthickness in the injection mold, the injection mold can operate at areasonable and economical production rate. However, the necessity foradditional preblow molds and additional cores and transfer means greatlycomplicates the apparatus and requires greater capital investment.Furthermore; pre-blowing to an intermediate shape is actually somewhatself-defeating in that it sacrifices the amount of orientation which maybe subsequently imparted to the parison, since the degree of orientationwhich may be imposed is directly proportional to the amount of stretchwhich takes place after the parison has been brought to the desiredorientation temperature, which in this case takes place in the pre-blowmold. Obviously, the amount of orientation-stretching which can beaccomplished from stretching the parison's intermediate shape to itsfinal shape is less than if the parison was stretched, at orientationtemperature, from its original shape to its final shape.

In Valyi, U.S. Pat No. 4,151,248, the need for pre-blow molds with itsattendant sacrifice in the levels of orientation which may be achieved,is avoided by a method for preparing hollow oriented plastic articleswherein a parison is formed and cooled rapidly on a first core in aninjection mold to an average temperature suited for orientation buthaving unequal distribution of temperature across the walls of saidparison, being cold on the outer surfaces and hot in the middle. Next,the cooled parison on said first core is transferred to a tempering moldwhere it is stripped from said first core and deposited in the temperingmold. The cooled parison is then conditioned or tempered in thetemperature controlled tempering mold to equalize the temperaturedistribution across the walls of the parison and attain a uniformtemperature distribution corresponding to the desired orientationtemperature of the thermoplastic material being molded. The tempering isaided by insertion of a separate stretch-blow core into and against theparison, to provide pressure contact between the parison and thetempering mold, thereby speeding heat transfer between the two. Thetemperature conditioned parison is then transferred on the stretch-blowcore to a third mold, which is the stretch blow mold, and is finallyaxially stretched by telescoping extension of said stretch-blow core,and then radially expanded and cooled in said stretch-blow mold, to forma biaxially oriented hollow article. Because the parison need not beconditioned to a uniform orientation temperature across its wallthickness in the injection mold, the parison may be removed from theinjection mold early, and the injection molding step can be operated ata reasonable rate, and much faster then otherwise would be possible.However, the necessity for additional cores, molds, and transfer meansgreatly complicates the apparatus and substantially adds to the costs.

In Marcs, U.S. Pat. No. 3,776,991, a method for producing biaxiallyoriented hollow plastic articles in a rotary type injection moldingmachine is disclosed having at least four stations, wherein a parison isformed on a first core within an injection mold at the injectionstation, cooled in the injection mold to a temperature above theorientation temperature, indexed to an interim station on said firstcore where the parison is preblown against the cold surfaces of aninterim mold, which is larger than the shape of the original parison butsmaller than the shape of the final desired article, cooled in theinterim mold to the optimum orientation temperature, indexed on saidfirst core to a blow station and positioned within the final blow moldwhose cavity is in the shape of the final desired article. The preblownparison is then axially stretched in the closed final blow mold byextension by a poppet valve stem located within said first core rod, andfinally radially expanded outward to its final shape, against the cavitywalls of the blow mold, and then cooled to a suitable ejectiontemperature. After opening the blow molds, the core rod and biaxiallyoriented article are indexed to an ejection station, where the biaxiallyoriented article is removed. This method dispenses with the need foradditional cores taught by the Valyi patents, but still requires the useof a pre-blow, or interim mold and interim mold station, with theirattendant complexities and high costs. In this method there is somesacrifice of the capability to impart high levels of orientation,because the article is stretched less in going from the interim shape tothe final shape, as compared to the stretching possible in othertechniques wherein the parison is stretched at orientation temperaturefrom the original parison shape to the final article shape.

Marcus, U.S. Pat. No. 4,065,246, teaches another injection blow moldingprocess employing at least three stations wherein the parison is formedon a core in an injection mold, cooled to the desired orientationtemperature range while in the injection mold, transferred on the samecore to the final blow mold and allowed to dwell therein to bring theparison to uniform orientation temperature while the outer tip of theparison is in contact with a temperature controlled stop, and theremainder of the parison, except for the inner surface of its tip, isexpanded slightly off the core to aid in the removal of the first corefrom said parison, by momentarily introducing low pressure air insidethe parison. Alternatively, Marcus teaches that lubricant may be used toaid in removal of the first core from the parison. Next, the first coreis removed from the partially expanded parison, and a second core isinserted and extended outwardly therein to stretch the parisonlongitudinally and thereby axially orient the parison. High pressure airis then introduced within the axially stretched parison to expand itradially outward until it contacts the cool surfaces of the blow moldcavity where it assumes its final shape and is cooled to a suitableejection temperature. The biaxially oriented article is then transferredon said second core to an ejection station where it is ejected from theapparatus. This process avoids the duplication of molds but requires theduplication of cores and transfer means, and extra stations, all ofwhich add complexities and additional costs.

The methods disclosed in these patents are typical beverage containermanufacturing methods. However, any method that can convenientlymanufacture PET beverage container can be used with the pellets of theinvention.

Similar to the methods shown above, a laminated bottle can be madehaving an exterior layer typically comprising a thermoplastic with aninterior layer comprising a barrier polymer. Either the barrier polymeror the polyester material or both can contain the modified orderivatized cyclodextrin material as a permeant trapping molecule or asa contaminate trapping molecule. The barrier polymer material can be anyconventional thermoplastic that can be formed with polyethyleneterephthalate into a laminate beverage container.

Thermoplastic materials can be formed into barrier film layer in thebottle using a variety of processes. These methods are well knownmanufacturing procedures. The characteristics in the polymerthermoplastics that lead to successful barrier film formation are asfollows. Skilled artisans manufacturing thermoplastic polymers havelearned to tailor the polymer material for thermoplastic processing andparticular end use application by controlling molecular weight (the meltindex has been selected by the thermoplastic industry as a measure ofmolecular weight—melt index is inversely proportional to molecularweight, density and crystallinity). For blown thermoplastic extrusionpolyolefins, such as low density polyethylene (LDPE), linear low densitypolyethylene (LLDPE) or high density polyethylene (HDPE) are the mostfrequently used thermoplastic polymers, although polypropylene, nylon,nitrites and polycarbonate are sometimes used to make blown film.Polyolefins typically have a melt index from 0.2 to 3 grams/10 mins., adensity of about 0.910 to about 0.940 grams/cc. For biaxially orientedfilm extrusion the polymer most often used are olefin based—chieflypolyethylene and polypropylene (melt index from about 0.1 to 4,preferably 0.4 to 4 grams/10 mins. Polyesters and nylons can also beused. For casting, molten thermoplastic resin or monomer dispersion aretypically produced from polyethylene or polypropylene. Occasionally,nylon, polyester and PVC are cast. For roll coating of aqueous basedacrylic urethane and PVDC, etc., dispersions are polymerized to anoptimum crystallinity and molecular weight before coating.

A variety of thermoplastic materials are also used. Such materialsinclude polyacrylonitrile, poly(acrylonitrile-co-butadiene-co-styrene)polymers, acrylic polymers such as the polymethylmethacrylate,poly-n-butyl acrylate, poly(ethylene-co-acrylic acid),poly(ethylene-co-methacrylate), etc.; cellophane, cellulosics includingcellulose acetate, cellulose acetate proprionate, cellulose acetatebutyrate and cellulose triacetate, etc.; fluoropolymers includingpolytetrafluoroethylene (TEFLON), poly(ethylene-co-tetrafluoroethylene)copolymers, (tetrafluoroethylene-co-propylene) copolymers, polyvinylfluoride polymers, etc., polyamides such as nylon 6, nylon 6,6, etc.;polycarbonates; polyesters such as poly(ethylene-co-terephthalate),poly(ethylene-co-1,4-naphthalene dicarboxylate),poly(butylene-co-terephthalate); polyimide materials; polyethylenematerials including low density polyethylene; linear low densitypolyethylene, high density polyethylene, high molecular weight highdensity polyethylene, etc.; polypropylene, biaxially orientedpolypropylene; polystyrene; vinyl films including polyvinyl chloride,(vinyl chloride-co-vinyl acetate) copolymers, polyvinylidene chloride,polyvinyl alcohol, (vinyl chloride-co-vinylidene dichloride) copolymers,specialty films including polysulfone, polyphenylene sulfide,polyphenylene oxide, liquid crystal polyesters, polyether ketones,polyvinylbutyrl, etc.

In making a laminate preform material having an exterior layer of apoly(ethylene-terephthalate) and an interior layer of a barrier polymer,a preform can be made through sequential injection molding techniques.The first step involves the injection molding of a first preformedsection. The preform section can comprise either the barrier polymer orthe polyethylene terephthalate container material. The preform can thenbe transferred to a second station wherein the complimentary polymer iseither injection molded on the interior of the preform (barrier polymerinside PET) or formed on the exterior of the preform (PET over thebarrier polymer). Such a multi-step formation can also be done on asingle machine having the appropriate internal working components forsuch injection molding operations. Between stages in the operation, thepreforms must be cooled to a sufficient temperature to permit successfulmanufacture. Additional layers can be used if desired, however, thepreferably container is a two layer construction. The two or more layerpreform material is then subjected to a reheat blow molding operation.The preform is reheated to a desirable temperature sufficient to permitblow molding into the desired shape. Not only does the blow moldingoperation achieved biaxial orientation of the layers, thereby improvingstrength, but also produces the desired end product, and shaped bottomif desired.

In the blow molding operation, the heat source is used either in theinterior of or around the exterior of the bottle preform to reach anappropriate blow molding temperature. In the preferred embodiment, theinjection molded by component preform is subject to a final formingoperation including biaxial orientation through stretch blow molding ata temperature from about at an elevated blow molding temperature that istypically 95-150° C. A isothermal temperature profile across the layersof thermoplastic is desired. The temperature of blow molding should besufficient to achieve satisfactory blow molding of both thermoplasticresins.

The cyclodextrin materials can be incorporated into a barrier cellulosicweb by coating the cellulosic web or a similar structure containing acellulosic layer with a liquid coating composition containing aneffective amount of a cyclodextrin or substituted cyclodextrin. Suchcoating compositions are typically formed using a liquid medium. Liquidmediums can include an aqueous medium or organic solvent media. Aqueousmedia are typically formed by combining water with additives andcomponents that can form a useful coatable aqueous dispersion. Solventbased dispersions based on organic solvents can be made using knowncorresponding solvent base coating technology.

In forming the barrier layers of the invention, coatings can be formedeither on a film which is later laminated on a film which is laterlaminated onto the cellulosic web or can be coated to form a film on thecellulosic web. Such coating processes involve the application of liquidto a traveling cellulosic web. Such coating processes commonly usemachines having an application section and a metering section. Carefulcontrol of the amount and thickness of the coating obtains optimizedbarrier layers without waste of material. A number of coating machinesare known such as tension sensitive coaters, for example, coaters usinga metering rod, tension insensitive coating stations that can maintaincoat weight even as web tensions vary, brush coating methods, air knifecoaters, etc. Such coating machines can be used to coat one or bothsides of a flexible film or one or both sides of a cellulosic web.

Coating machines described above commonly apply a liquid compositioncontaining a film forming material, additives that can help form andmaintain the coating composition along with the effective amount of thecyclodextrin or substituted cyclodextrin material. The film formingmaterials are often called a binder. Such binders exist in the finalcoating as a polymer of high molecular weight. Thermoplastic polymers orcrosslinking polymers can both be used. Such binders are grouped intocertain overlapping classes including acrylic, vinyl, alkyl, polyester,etc. Further, the compositions described above are materials that can beused in forming the polymer films also have corresponding materials thatcan be used in the formation of aqueous and solvent based coatingcompositions. Such coating compositions can be made by combining theliquid medium with solid materials containing the polymer, thecyclodextrin and a variety of useful additives. Commonly, thecyclodextrin materials added to the coating composition as part of thesolids component. The solids present in the coating composition cancontain from about 0.01 to about 10 wt % of the cyclodextrin compound,preferably about 0.1 wt % to 5 wt %, most preferably about 0.1 wt % toabout 2 wt % of the cyclodextrin material based on the total solids inthe solvent based dispersion composition.

A useful barrier layer can also be made by coating the interior ofeither a preform or a formed container with a coating typically madefrom an aqueous dispersion or suspension of a useful polymer materialcontaining the modified cyclodextrin material. In a preferred process,the preform or container is heated to 40° to 80° C., and in coated withan aqueous dispersion of a polymer, and dried.

The coating is applied at a temperature of 40° to 100° C., preferably50° to 90° C. If the temperature is below 40° C., little advantage isobtained compared with coating a preform at a room temperature whereonly a very thin coating, e.g. about 3 μm thickness, of insufficientadhesion is obtained. If the preform is heat to above 90° C., thencrystallization is likely to be induced which impairs satisfactoryconversion of the preform into a biaxially oriented container during theblow molding operation and also gives rise to distortion of thecontainer as a result of uneven relaxation of molding strains.

Notwithstanding the need to prevent an undue degree of bulkcrystallization in the preform which would be caused by heating, it canbe beneficial to encourage surface crystallization of the preform bypre-treatment with a suitable solvent, for example butanone (methylethyl ketone). Such treatment results in a surface roughness which aidsthe keying of subsequently applied coatings to the preform. The effectis directly proportional to both time and temperature of treatment, andwith butanone for example a fine-scale (about 1 μm) roughness,associated with a well-developed spherulitic texture extending 30 to 50μm inward from the surface, is obtained by treating at 40° to 90° C. fora period of 1 to 2 minutes.

Other solvents that may be used include acetone, chloroform ethylacetate, m-cresol and trichloroethylene. By coating a temperature in therange 40 to 90° C. an adherent and uniform coating of greater thickness,e.g. of the order of 20 to 30 μm may be produced in a single coatingstep. If this thickness coating is inadequate, the coated perform may begiven further coats after drying to give the necessary thickness.Preferably the coated article is reheated to 40 to 80° C. beforeapplying such further coats.

In order to avoid undue heating of the amorphous PET during the dryingof the aqueous dispersion, which heating could give rise to developmentof crystallinity in the PET preform, the drying is preferably conductedusing an infra- red heater operating at a temperature below 1000° C. Atoperating temperatures below 1000° C. the radiation will be absorbed bythe water in the aqueous dispersion without unduly heating the PETpreform itself: the water thus tends to act as a filter againstinfra-red radiation.

During the drying step, the preform or bottle may be rotated so as toprovide even heating and also to provide an even thickness coating. Thusa PET preform in the form of a tube having one closed end may be mountedwith its longitudinal axis horizontal and rotated about thislongitudinal axis.

If desired multiple coatings may be applied continuously to the PET.Thus the preform or bottle may be mounted with its longitudinal axishorizontal and rotated about the longitudinal axis. As it rotates it isfirst heated by an infra-red heater to 40° to 90° C. and then it picksup a coating of the aqueous dispersion from a coating point, e.g. aflexible doctor knife, then the water is evaporated off, and the coatedpreform heated to 40° to 90° C., by means of one or more infra-redheaters mounted adjacent the rotating article so that the coating isdried and the preform reheated before one revolution of the preform iscompleted: hence on reaching the coating point on completion of onerevolution, a further coating of the aqueous dispersion is applied overthe dried coating. Thus a multilayer coating may be formed as a spiralon the preform.

The coating may be applied to the interior or exterior surface and maybe applied by spraying or dip coating.

We have found coating the interior to be advantageous particularly wherethe resultant bottle is intended to contain carbonated beverages. Thusit presents a barrier layer between the beverage and bottle wall and soreduces the amount of carbon dioxide absorbed by the polyethyleneterephthlate itself. This enables thinner coatings to be employed toachieve a specified carbon dioxide loss. Thus, in some cases, it ispossible to employ a coating on the interior of the preform of thicknessonly half that which would be required on the outside of the preform togive a similar carbon dioxide loss.

Furthermore, when used to make bottles for carbonated beverages, thereis a tendency for the carbon dioxide diffusing through the bottle wallto cause an exterior coating to lose adhesion after a period of timegiving rise to blisters. In contrast, a coating on the interior surfacewill be held firmly in place, even if the adhesion is lost for somereason, by the pressure of the carbonated liquid.

The polymer dispersion may be any of those that are customarily employedfor application of barrier coatings to plastic materials. Preferably itis an aqueous dispersion of a copolymer of vinylidene chloride withacrylonitrile and/or methyl acrylate optionally containing units derivedfrom other monomers such as methyl methacrylate, vinyl chloride, acrylicacid or itaconic acid. Particularly useful vinylidene chloridecopolymers are those containing 5 to 10% by weight of units derived fromacrylonitrile and/or methyl acrylate, and optionally containing up tolot by weight of units derived from an unsaturated carboxylic acid suchas acrylic acid. The dispersions may preferably contain surfactants suchas sodium alkyl sulphonates.

The containers of the invention can be used to distribute a variety ofbeverages including milk (skim, 1%, 2%, chocolate), orange juice,carbonated beverages, water, flavored water, carbonated water, beer,mixed alcoholic drinks, distilled spirits, wines, 200 proof grain orabsolute alcohol; fruit juices such as apple, tomato, pear, etc.;distilled water, etc.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 is a generally isometric view of a conceptual representation ofthe dimensions of the various cyclodextrin molecules. FIG. 1 shows an α,β and γ cyclodextrin showing the dimensions of the exterior of thecyclodextrin ring along with the dimensions of the interior pore volumethat can act as a trapping site for permeants or polymer impurities. Thefigure shows that the primary and secondary hydroxyls exist on the edgeof the circular form. This suggests that the interior of thecyclodextrin is relatively hydrophobic and adapted to complex andcontain hydrophobic molecules.

FIG. 2 is a side view of a substantially transparent two litercarbonated beverage container. The container generally shown at 20comprises a body 22, a base 24 and a cap portion 26. The overall shapeof the container is 30 formed in a thermoplastic blow molding operation.Base 24 is a self-supporting base formed during bottle manufacture. Sucha bottle can contain either a second layer prepared from a parisonhaving a second thermoplastic material formed during parison formationor can have a second layer derived from a liquid coating material. Theliquid coating material can be either a parison coating or a bottlecoating.

The foregoing discussion illustrates various embodiments of theapplication under the barrier and trapping properties of the materialsof the invention. The following examples and data further exemplify theinvention and contain a best mode.

As a model for beverage containers we made films and tested the filmsfor barrier properties. We have found that the cyclodextrin material canbe melt blended into thermoplastic materials smoothly resulting in clearextrudable thermoplastic materials with the cyclodextrin materialsuniformly distributed throughout the thermoplastic. Further, we havefound that the cyclodextrin derivatives can be combined with a broadvariety of thermoplastic films. The cyclodextrin materials can beincorporated into the films in a broad range of cyclodextrinconcentrations. The cyclodextrin containing thermoplastic materials canbe blown into films of varying thickness and can be blown free of meltfracture or other film or sheet variation. We have found in ourexperimentation that the barrier properties, i.e. reduction intransmission rate of aromatic hydrocarbons, aliphatic hydrocarbons,ethanol and water vapor can be achieved using the cyclodextrinderivative technology. We have also found that the use of cyclodextrinmaterials improve the surface properties of the film. The surfacetension of the film surface and surface electrical properties were alsoimproved. Such a result increases the utility of the films of theinvention in coating, printing, laminating, handling, etc. In initialwork we have also found (1) several modified cyclodextrin candidateswere found to be compatible with the LLDPE resin and provide goodcomplexation of residual LLDPE volatile contaminants as well as reduceorganic permeants diffusing through the film. (2) Unmodified βCDadversely affects transparency, thermal stability, machinability, andbarrier properties of the film. Conversely, selected modified βCD(acetylated and trimethylsilyl ether derivatives) have no affect ontransparency and thermal stability. The machinability of the extrudedplastic material is effected somewhat causing some surface defects,thereby reducing the barrier properties of the film. (3) Filmscontaining a modified βCD composition (1% by weight) reduce aromaticpermeants by 35% at 72° F. and 38% at 105° F.; aliphatic permeants werereduced by only 9% at 72° F. These results would improve significantlyif worst case shelf-life testing conditions were not used to test thefilms. (4) Complexation rates were different for aromatic and aliphaticpermeants. Films containing modified βCD had better complexation ratesfor aromatics (gasoline-type compounds) than aliphatic (printingink-type compounds). Conversely, film coating had significantly bettercomplexation of aliphatic compound than aromatic compounds. (5) βCDcontaining acrylic coatings were the star performers reducing aliphaticpermeants from 46% to 88%, while aromatics were reduced by 29%.

QUALITATIVE PREPARATION

Initially, we produced four experimental test film models. Three of thefilms contained β-cyclodextrin βCD at loading of 1%, 3% and 5% (wt./wt.)while the fourth was a control film made from the same batch of resinand additives but without βCD. The 5% loaded βCD film was tested forcomplexation of residual organic in the test film. Even though βCD wasfound to effectively complex residual organics in the linear low densitypolyethylene (LLDPE) resin, it was incompatible with the resin andformed βCD particle agglomerations.

We have evaluated nine modified βcyclodextrins and a milledβ-cyclodextrin (particle size 5 to 20 microns). The differentcyclodextrin modifications were acetylated, octanyl succinate,ethoxyhexyl glycidyl ether, quaternary amine, tertiary amine,carboxymethyl, succinylated, amphoteric and trimethylsilyl ether. Eachexperimental cyclodextrin (1% loading wt/wt) was mixed with low densitypolyethylene (LLDPE) using a Littleford mixer and then extruded using atwin screw Brabender extruder.

The nine modified cyclodextrin and milled cyclodextrin LLDPE profileswere examined under an optical microscope at 50× and 200× magnification.The microscopic examination was used to visually check for compatibilitybetween LLDPE resin and cyclodextrin. Of the ten cyclodextrin candidatestested, three (acetylated, octanyl succinate and trimethylsilyl ether)were found visually to be compatible with the LLDPE resin.

Complexed residual film volatiles were measured using cryotrappingprocedure to test 5% βCD film sample and three extruded profilescontaining 1% (wt/wt) acetylated βCD octanyl succinate βCD andtrimethylsilyl ether. The method consists of three separate steps; thefirst two are carried out simultaneously while the third, aninstrumental technique for separating and detecting volatile organiccompounds, is conducted after one and two. In the first step, an inertpure, dry gas is used to strip volatiles from the sample. During the gasstripping step, the sample is heated at 120° C. The sample is spikedwith a surrogate (benzene-d6) immediately prior to the analysis.Benzene-d₆ serves as an internal QC surrogate to correct each set oftest data for recovery. The second step concentrates the volatilesremoved from the sample by freezing the compounds from the stripping gasin a headspace vial immersed in a liquid nitrogen trap. At the end ofthe gas-stripping step, an internal standard (toluene-d8) is injecteddirectly into the headspace vial and the vial is capped immediately.Method and system blanks are interspersed with samples and treated inthe same manner as samples to monitor contamination. The concentratedorganic components are then separated, identified and quantitated byheated headspace high resolution gas chromatography/mass spectrometry(HRGC/MS). The results of the residual volatile analyses are presentedin the table below:

TABLE 1 % Volatile Complexation Sample Identification as Compared toControl 5% βCD Blown Film 80 1% Acylated βCD Profile 47 1% OctanylSuccinate βCD Profile 0 1% Trimethylsilyl ether Profile 48 1% βCD MilledProfile 29

In these preliminary screening tests, βCD derivatives were shown toeffectively complex trace volatile organics inherent in low densitypolyethylene resin used to make experimental film. In 5% βCD loadedLLDPE film, approximately 80% of the organic volatiles were complexed.However, all βCD films (1% and 5%) had an off-color (light brown) andoff-odor. The color and odor problem is believed to be the result ofdirect decomposition of the CD or impurity in the CD. Two odor-activecompounds (2-furaldehyde and 2-furanmethanol) were identified in theblown film samples.

Of the three modified compatible CD candidates (acetylated, octanylsuccinate and trimethylsilyl ether), the acetylated and trimethylsilylether CD were shown to effectively complex trace volatile organicsinherent in the LLDPE resin. One percent loadings of acetylated andtrimethylsilyl ether (TMSE) βCD showed approximately 50% of the residualLPDE organic volatiles were complexed, while the octanyl succinate CDdid not complex residual LLDPE resin volatiles. Milled βCD was found tobe less effective (28%) than the acetylated and TMSE modified βCD's.

Plastic packaging materials all interact to some degree with the foodproduct they protect. The main mode of interaction of plastic packagingof food is through the migration of organic molecules from theenvironment through the polymer film into the head space of the packagewhere they are absorbed by the food product. Migration or transfer oforganic molecules of the package to the food, during-storage, iseffected by environmental conditions such as temperature, storage time,and other environmental factors (e.g., humidity, type of organicmolecules and concentration thereof). Migration can have both quality(consumer resistance) and toxicological influence. The objective ofpackaging film testing is to measure how specific barriers may influencethe quality of packaged individual foods. To simulated acceleratedshelf-life testing for low-water-activity food products, the testing wasconducted at a temperature of 72° F. and 105° F., and a relativehumidity of 60%. These temperature and humidity conditions are probablysimilar to those found in uncontrolled warehouses, in transit, and instorage.

If a polymer is moisture sensitive, the relative humidity can affect thefilm's performance especially in low-water-activity food products.Because a packaging film during actual end-use conditions will beseparating two moisture extremes, relative humidity in the permeationdevice was controlled on both sides of the film. The environment side,representing the outside of the package, was maintained at 60% relativehumidity, and the sample side, representing the inside of a packagecontaining a low-water-activity product, at 0.25.

A combination of permeants was used to measure the function andperformance of the CD. A combination was used to be realistic, sincegasoline (principally an aromatic hydrocarbon mixture) and printing inksolvents (principally an aliphatic hydrocarbon mixture) are not formedfrom a single compound but are a mixture of compounds.

The aromatic permeant contained ethanol (20 ppm), toluene (3 ppm),p-xylene (2 ppm), o-xylene (1 ppm), trimethyl-benzene (0.5 ppm) andnaphthalene (0.5 ppm). The aliphatic permeant, a commercial paintsolvent blend containing approximately twenty (20) individual compounds,was 20 ppm.

The permeation test device is described in U.S. Pat. No. 5,603,974,issued Feb. 18, 1997 to Wood et al., which is expressly incorporated byreference herein.

Experimental film performance was measured in the closed-volumepermeation device. High-resolution gas chromatograph (HRGC) operatedwith a flame ionization detector (FID) was used to measure the change inthe cumulative penetrant concentration as a function of time.Sample-side (food product side) compound concentrations are calculatedfrom each compound's response factor. Concentrations are reported inparts per million (ppm) on a volume/volume basis. The cumulativepenetrant concentration on the sample-side of the film is plotted as afunction of time.

We produced four experimental test films. Three of the films containedβCD at loading of 1%, 3% and 5% (wt/wt) while the fourth was a controlfilm made from the same batch of resin and additives but without βCD.

A second experimental technique was also undertaken to determine whetherβCD sandwiched between two control films will complex organic vaporspermeating the film. The experiment was carried out by lightly dustingβCD between two control film sheets.

The testing showed the control film performed better than βCD loadedfilms. The permeation test results also demonstrated the higher the βCDloading the poorer the film performed as a barrier. The test results forsandwiching βCD between two control films showed βCD being twice aseffective in reducing permeating vapors than the control samples withoutβCD. This experiment supported that CD does complex permeating organicvapors in the film if the film's barrier qualities are not changedduring the manufacturing process making the film a less effectivebarrier.

The 1% TMSE βCD film was slightly better than the 1% acetylated βCD film(24% -vs- 26%) for removing aromatic permeants at 72° F. adding moremodified CD appeared to have no improvement.

For aromatic permeants at 105° F., both 1% TMSE βCD and 1% acetylatedβCD are approximately 13% more effective removing aromatic permeantsthan 72° F. The 1% TMSE film was again slightly better than the 1% film(36% -vs- 31%) for removing aromatic permeants.

The 1% TMSE film was more effective initially removing aliphaticpermeants than the 1% acetylated βCD film at 72° F. But for the durationof the test, 1% TMSE βCD was worse than the control while 1% acetylatedβCD removed only 6% of the aliphatic permeants.

We produced two experimental aqueous coating solutions. One solutioncontained hydroxyethyl βCD (35% by weight) and the other solutioncontained hydroxypropyl βCD (35 by weight). Both solutions contained 10%of an acrylic emulsion comprising a dispersion of polyacrylic acidhaving a molecular weight of about 150,000 (Polysciences, Inc.) (15%solids by weight) as a film forming adhesive. These solutions were usedto hand-coat test film samples by laminating two LLDPE films together.Two different coating techniques were used. The first technique veryslightly stretched two film samples flat, the coating was then appliedusing a hand roller, and then the films were laminated together whilestretched flat. The Rev. 1 samples were not stretched during thelamination process. All coated samples were finally placed in a vacuumlaminating press to remove air bubbles between the film sheets. Filmcoating thicknesses were approximately 0.0005 inches. These CD coatedfilms and hydroxylmethyl cellulose coated control films weresubsequently tested.

A reduction in aromatic and aliphatic vapors by the hydroxyethyl βCDcoating is greater in the first several hours of exposure to the vaporand then diminishes over the next 20 hours of testing. Higher removal ofaliphatic vapors than aromatic vapors was achieved by the hydroxyethylβCD coating; this is believed to be a function of the difference intheir molecular size (i.e., aliphatic compounds are smaller thanaromatic compounds). Aliphatic permeants were reduced by 46% as comparedto the control over the 20 hour test period. Reduction of aromaticvapors was 29% as compared to the control over the 17 hour test period.

The Rev. 1 coated hydroxyethyl βCD reduced the aliphatic permeants by87% as compared to the control over the 20 hour test period. It is notknown if the method of coating the film was responsible for theadditional 41% reduction over the other hydroxyethyl βCD coated film.

The hydroxyethyl βCD coating was slightly better for removing aromaticpermeants than the hydroxypropyl βCD coating (29% -vs- 20%) at 72° F.

LARGE SCALE FILM EXPERIMENTAL Preparation of Cyclodextrin DerivativesExample I

An acetylated β-cyclodextrin was obtained that contained 3.4 acetylgroups per cyclodextrin on the primary —OH group.

Example II Trimethyl Silyl Ether of β-cyclodextrin

Into a rotary evaporator equipped with a 4000 milliliter round bottomflask and a nitrogen atmosphere, introduced at a rate of 100 millilitersN₂ per minute, was placed three liters of dimethylformamide. Into thedimethylformamide was placed 750 grams of β-cyclodextrin. Theβ-cyclodextrin was rotated and dissolved in dimethylformamide at 60° C.After dissolution, the flask was removed from the rotary evaporator andthe contents were cooled to approximately 18° C. Into the flask, placedon a magnetic stirrer and equipped with a stir bar, was added 295milliliters of hexamethyldisilylazine (HMDS-Pierce Chemical No. 84769),followed by the careful addition of 97 milliliters oftrimethylchlorosilane (TMCS—Pierce Chemical No. 88531). The carefuladdition was achieved by a careful dropwise addition of an initialcharge of 20 milliliters and after reaction subsides the carefuldropwise addition of a subsequent 20 milliliter portions, etc. untiladdition is complete. After the addition of the TMCS was complete, andafter reaction subsides, the flask and its contents were placed on therotary evaporator, heated to 60° C. while maintaining an inert nitrogenatmosphere flow of 100 milliliters of N₂ per minute through the rotaryevaporator. The reaction was continued for four hours followed byremoval of solvent, leaving 308 grams of dry material. The material wasremoved from the flask by filtering, washing the filtrate with deionizedwater to remove the silylation products, vacuum oven drying (75° C. at0.3 inches of Hg) and stored as a powdered material and maintained forsubsequent compounding with a thermoplastic material. Subsequentspectrographic inspection of the material showed the β-cyclodextrin tocontain approximately 1.7 trimethylsilylether substituent perβ-cyclodextrin molecule. The substitution appeared to be commonly on aprimary 6-carbon atom.

Example III

An hydroxypropyl β-cyclodextrin was obtained with 1.5 hydroxypropylgroups per molecule on the primary 6-OH group of the βCD.

Example IV

An hydroxyethyl β-cyclodextrin was obtained with 1.5 hydroxyethyl groupsper molecule on the primary 6-OH group of the βCD.

Preparation of Films

We prepared a series of films using a linear low density polyethyleneresin as a beverage container model. βCD and derivatized βCD such as theacetylated or the trimethylsilyl derivative of a β-cyclodextrin wereused. The polymer particles were dry blended with the powderedβ-cyclodextrin and β-cyclodextrin derivative material, a fluoropolymerlubricant (3M) and the antioxidant until uniform in the dry blend. Thedry blend material was mixed and extruded in a pellet form in a HaakeSystem 90, ¾″ conical extruder. The resulting pellets were collected forfilm preparation.

Table 1A displays typical pelletizing extruder conditions. The filmswere blown in an extruder as described in U.S. Pat. No. 5,603,974,issued Feb. 18, 1997 to Wood et al., which is expressly incorporatedherein. The film is manufactured according to the above protocol andreported in Table IB. The film was tested for transmission rates at avariety of environmental conditions. Environmental test conditions areshown below in Table II. The film is manufactured according to the aboveprotocol and reported in Table IB. The film was tested for transmissionrates at a variety of environmental conditions. Environmental testconditions are shown below in Table II.

TABLE IA 0.5% TMSE Pelletizing 1-19-94 0 min Torque 4866 meter-grainRotor 198 rpm Run Time 13 sec Tot. Torque 0.0 mkg-min Aux. 0% Channels--1-- --2-- --3-- --4-- --5-- --6-- Melt Temp  37  41  41  41 41 ° C.Set Temp 150 160  160 170  0 0 ° C. Deviation  0  0   0  0  0 0 ° C.Cooling Yes Yes Yes Yes Pressure  0  0 2739  0  0 psi

TABLE IB Extruded Films (Exxon LL3201) Made with Low DensityPolyethylene Roll Fluoropolymer Extruder Temp. Melt Die Temp. Die No.Sample ID Additive¹ Zone 3 (F.) Temp (F.) Zone 3 (F.) Lbs./Hr RPM GapComments 1 Control 500 ppm 428 406 406 30.1 50 24 2   1% Ex. I 1000 ppm 441 415 420 29.7 50 35 3   1% Ex. I 1000 ppm  441 416 420 28.5 50 35 4  1% Ex. I 500 ppm 441 415 420 29.9 50 35 5   1% Ex. I 500 ppm 418 405414 29.9 50 35 6   1% Ex. I 500 ppm 421 397 414 29.0 50 35 7 0.5% Ex. I500 ppm 421 403 415 29.0 50 35 8   2% Ex. I 500 ppm 421 404 415 27.7 5035 Very slight melt fracture 9   1% Ex. II 500 ppm 421 406 415 28.3 5035 Particles in film. 10   1% Ex. II 500 ppm 426 410 415 26.7 50 35Particles in film. 11   1% Ex. II 500 ppm 432 415 414 29.0 50 35Particles in film. Very slight yellowing to film. 12   1% Ex. II 500 ppm431 414 415 21.5 39 35 Particles in film. 13 0.5% Ex. II 500 ppm 431 415415 27.7 50 35 Particles in film. 14 0.5% Ex. II 500 ppm 425 410 41528.9 50 35 Particles in film. 15   2% Ex. II 500 ppm 410 414 415 20.2 3835 Particles in film. Very slight yellowing to film. 16   2% Ex. II 500ppm 422 415 415 20.5 38 35 Particles in film. Very slight yellowing tofilm. 17   2% Ex. II 500 ppm 422 416 415 20.5 38 35 Particles in film.Very slight yellowing in film. ¹Also contains 500 ppm Irganox 1010antioxidant and 1000 ppm IrgaFos 168.

TABLE II Test Conditions Roll Sample Temp. Sample Environ. ID Number(F.) Side Side Permeant² Roll #2 72 Rm % RH Rm % RH Aromatic/AlcoholRoll #3 Roll #5 Roll #6 Roll #5 72 Rm % RH Rm % RH Aromatic/Alcohol Roll#8 Roll #7 72 0.25 Aw 60% RH Aromatic/Alcohol Roll #5 Roll #8 Roll #7 72 .60 Aw 30% RH Aromatic/Alcohol Roll #5 Roll #8 Roll #2 105 Rm % RH Rm %RH Aromatic/Alcohol Roll #3 Roll #4 Roll #5 Roll #6 Roll #8 Roll #12Roll #7 105 0.25 Aw 15% RH Aromatic/Alcohol Roll #5 Roll #8 Roll #13 72Rm % RH Rm % RH Aromatic/Alcohol Roll #14 Roll #9 Roll #9 Roll #11 Roll#12 Roll Sample Temp. Sample Environ. ID Number (F.) Side Side Permeant³⁴ Roll #15 Roll #16 Roll #17 Roll #14 105 Rm % RH Rm % RHAromatic/Alcohol Roll #15 10% Ex. III in PVdC 72 0.25 Aw 60% RHAromatic/Alcohol 20% Ex. III in PVdC 5% Ex. III/ Acrylic 72 Rm % RH Rm %RH Aromatic/Alcohol 10% Ex. III/ Acrylic Roll #7 72 Rm % RH Rm % RHNaphtha Roll #5 Roll #8 Roll #12 72 Rm % RH Rm % RH Naphtha Roll #15 ²7ppm aromatic plus 20 ppm ETOH. ³7 ppm aromatic plus 20 ppm ETOH. ⁴40 ppmNaphtha

The results of the testing show that the inclusion of a compatiblecyclodextrin material in the thermoplastic films of the inventionsubstantially improves the barrier properties by reducing transmissionrate of a variety of permeants. The data showing the improvement intransmission rate is shown below in the following data tables.

Comparison of Transmission Rates in Modified β-Cyclodextrin - LPDE FilmsAromatics % Tot. Volatiles % Naphtha % Sample Aromatic Improvement TotalVolatiles Improvement Improvement Identification Transmission Rate* OverControl Transmission Rate* Over Control Over Control Temperature 72° F.Sample Side: Room % RH Environment: Room % RH Control Film 3.35E-04 0%3.79E-04 0% 1.0% CS-001 3.18E-04 5% 3.61E-04 5% (Roll #2) 1.0% CS-0012.01E-04 40% 2.55E-04 33% (Roll #3) 1.0% CS-001 2.67E-04 20% 3.31E-0413% (Roll #5) 1.0% CS-001 3.51E-04 −5% 3.82E-04 −1% (Roll #6) ControlFilm (Roll #1) 7.81E-03 0% 0.5% CS-001 (Roll #7) 7.67E-03 2% 1% CS-001(Roll #5) 7.37E-03 6% 2% CS-001 (Roll #8) 6.53E-03 16% Control Film5.16E-04 0% 5.63E-04 0% (Roll #1) 1.0% CS-001 4.01E-04 22% 5.17E-04 8%(Roll #5) 2.0% CS-001 2.91E-04 44% 3.08E-04 45% (Roll #8) Control Film(Roll #1) 7.81E-03 0% 0.5% CS-001 (Roll #7) 7.67E-03 2% 1% CS-001 (Roll#5) 7.37E-03 6% 2% CS-001 (Roll #8) 6.53E-03 16% Temperature 72° F.Sample Side: 0.25 Aw Environment: 60% RH Control Film 3.76E-04 0%3.75E-04 0% (Roll #1) 0.5% CS-001 2.42E-04 36% 2.41E-04 36% (Roll #7) 1%CS-001 3.39E-04 10% 3.38E-04 10% (Roll #5) 2% CS-001 2.48E-04 34%2.47E-04 34% (Roll #8) Temperature 105° F. Sample Side: Room % RHEnvironment: Room % RH Control Film 1.03E-03 0% 1.13E-03 0% (Roll #1) 1%CS-001 5.49E-04 47% 5.79E-04 49% (Roll #2) 1% CS-001 4.74E-04 54%5.00E-04 56% (Roll #3) 1% CS-001 6.41E-04 38% 6.83E-04 40% (Roll #4) 1%CS-001 5.22E-04 49% 5.54E-04 51% (Roll #5) 1% CS-001 4.13E-04 60%4.39E-04 61% (Roll #6) 2% CS-001 5.95E-04 42% 6.18E-04 45% (Roll #8) 1%TMSE 8.32E-04 19% 8.93E-04 21% (Roll #12) Control Film 4.34E-04 0%4.67E-04 0% (Roll #1) 0.5% CS-001 4.03E-04 7% 4.41E-04 6% (Roll #7) 1.0%CS-001 5.00E-04 −15% 5.33E-04 −14% (Roll #5) 2.0% CS-001 3.96E-04 9%3.94E-04 16% (Roll #8) Temperature 72° F. Sample Side: Room % RHEnvironment: Room % RH Control Film 3.09E-04 0% 3.45E-04 0% 0.5% TMSE2.50E-04 19% 2.96E-04 14% (Roll #13) 0.5% TMSE 2.37E-04 23% 2.67E-04 33%(Roll #14) 1% TMSE 2.67E-04 14% 3.05E-04 12% (Roll #9) 1% TMSE 4.85E-04−57% 5.27E-04 −53% (Roll #10) 1% TMSE 2.58E-04 17% 2.92E-04 15% (Roll#11) 1% TMSE 2.15E-04 31% 2.55E-04 26% (Roll #12) 2% TMSE 2.54E-04 18%3.04E-04 12% (Roll #15) 2% TMSE 2.79E-04 10% 3.21E-04 7% (Roll #16) 2%TMSE 2.81E-04 9% 3.24E-04 6% (Roll #17) Control Film (Roll #1) 9.43E-030% 1% TMSE (Roll #12) 1.16E-02 −23% 2% TMSE (Roll #15) 1.56E-02 −65%Control Film 8.36E-04 0% 9.05E-04 0% (Roll #1) 0.5% TMSE 6.77E-04 19%7.25E-04 20% (Roll #14) 2% TMSE 6.36E-04 24% 6.81E-04 25% (Roll #15)Temperature 72° F. Sample Side: 0.25 Aw Environment: 60% RH PVdC Control6.81E-05 0% 1.05E-04 0% PVdC w/10% HP 1.45E-05 79% 2.39E-05 77% B-CyDPVdC w/20% HP 9.71E-05 −42% 1.12E-04 −7% B-CyD Temperature 72° F. SampleSide: Room % RH Environment: Room % RH Control Acrylic 2.07E-06 0%2.10E-05 0% 5% HP B-CyD/ 1.50E-06 27% 2.07E-05 1% Acrylic 10% HP B-CyD/4.13E-06 −100% 4.30E-05 −105% Acrylic $\begin{matrix}* \\\quad\end{matrix}\quad \frac{{{gm} \cdot 0.001}\quad {{in}.}}{100\quad {{in}^{2} \cdot 24}\quad {{hrs}.}}$

We prepared a series of aqueous coatings containing hydroxypropyl βCD,These coatings can be used to coat the interior or exterior of a bottle.One of the coatings was prepared from a 10% acrylic emulsion (apolyacrylic acid polymer having a molecular weight of about 150,000purchased from Polysciences, Inc.). The 10% acrylic emulsion containedhydroxypropyl βCD at a 5% and 10% by weight loading. These solutionswere used to hand-coat test film samples by laminating two films. Thecoatings were applied to linear low density polyethylene film sheetcontaining 0.5% acetylated βCD (Roll No. 7) and to a second film sheetcontaining 2% acetylated βCD (Roll No. 8) using a hand roller and thenlaminating the films. The films were not stretched during lamination.All coated samples were placed in a vacuum laminating press to removeair bubbles between the film sheets. The acrylic coating thickness wasabout 0.0002 inch. An acrylic coated control was prepared in anidentical manner containing no hydroxypropyl βCD. The multilayerstructure was tested with the 0.5% acetylated βCD film facing theenvironmental flask side of the test cell.

A second coating was prepared from a vinylidene chloride latex (PVDC, 60wt-% solids) purchased from Dagax Laboratories, Inc. The PVDC latexcoating was prepared with two levels of hydroxypropyl βCD-10% and 20% byweight of the derivatized cyclodextrin. These solutions were used tohand-coat linear low density polyethylene test film samples bylaminating the two films together. The coatings were applied to twocontrol film sheets (rolled into one) using a hand roller and laminatedtogether. The films were not stretched during lamination process. Allcoated samples were placed in a vacuum laminating press to remove airbubbles between the film sheets. The PVDC coating thickness wasapproximately 0.0004 inch. A PVDC coated control was prepared in anidentical manner but without hydroxypropyl βCD.

The data following the preparatory examples showing improvement intransmission rate was obtained using the following general test method.

Method Summary

This method involves experimental techniques designed to measure thepermeability of selected organic molecules through food packaging films,using a static concentration gradient. The test methodology simulatesaccelerated shelf-life testing conditions by implementing variousstorage humidities, product water activities and temperature conditionsand using organic molecule concentrations found in previously testedfood products to simulate outside-the-package organic vapors in thepermeation test cell. This procedure allows for the determination of thefollowing compounds: ethanol, toluene, p-xylene, o-xylene,1,2,4-trimethyl benzene, naphthalene, naphtha solvent blend, etc.

Threshold Environmental Odor Conc. Cell Conc. Test Compounds ul/L ppmul/L ppm Ethanol   5-5000 20 Toluene 0.10-20   3 p-Xylene 0.5 2 o-Xylene0.03-12   1 1,2,3-Trimethyl Benzene NA 0.5 Naphthalene 0.001-0.03  0.5Naphtha Solvent Blend NA 40

Table 1. Permeant Test Compounds

In a typical permeation experiment, three steps are involved. They are(a) the instrument sensitivity calibration, (b) film testing to measuretransmission and diffusion rates, and (c) the quality control of thepermeation experiment.

Film samples are tested in a closed-volume permeation device.High-resolution gas chromatograph (HRGC) operated with a flameionization detector (FID) is used to measure the change in thecumulative penetrant concentration as a function of time.

Sample-side and environment-side test compound concentrations arecalculated from each compound's response factor or calibration curve.Concentrations are then volume-corrected for each specific set ofpermeation cells if permeant mass is desired.

The cumulative penetrant concentration is plotted as a function of timeon both the upstream (environment) and downstream (sample) side of thefilm. The diffusion rate and transmission rate of the permeant arecalculated from the permeation curve data.

1.0 Equipment and Reagents 2.1 Equipment

Gas chromatograph (HP 5880) equipped with flame ionization detector, asix-port heated sampling valve with 1 ml sampling loop and dataintegrator

J&W capillary column. DB-5, 30M×0.250mm ID, 1.0 umdf.

Glass permeation test cells as previously referenced.

Permeation cell clamping rings (2).

Permeation cell aluminum seal rings (2).

Natural Rubber Septa. 8 mm OD standard-wall or 9 mm OD (Aldrich ChemicalCompany, Milwaukee, Wis.).

Assorted laboratory glass ware and syringes.

Assorted laboratory supplies.

2.2 Reagents

Reagent water. Water in which interferences are not observed at the MDLof the chemical analytes of interest. A water purification system isused to generate reagent water which has been boiled to 80% volume,capped, and allowed to cool to room temperature before use.

Stock Ethanol/Aromatic Standard solution. Ethanol (0.6030 gram), toluene(0.1722 gram), p-xylene (0.1327 gram), o-xylene (0.0666 gram),trimethylbenzene (0.0375 gram) and naphthalene (0.0400 gram) package in1 ml sealed glass ampules. Naphtha blends standard is a commercial paintsolvent blend containing approximately twenty (20) individual aliphatichydrocarbon compounds obtained from Sunnyside Corporation, ConsumerProducts Division, Wheeling, Ill.

Triton X-100. Nonylphenol nonionic surface active agent (Rohm and Hass).

2.0 Standards Preparation 2.2 Permeation Working Standard

A stock permeant test standard solution is used. These standards areprepared by weight from neat certified reference compounds, actualweight and weight percent are shown.

The working ethanol/aromatic standard is prepared by injecting 250 ul ofthe stock standard solution into 100 ml of reagent water containing 0.1gram of surfactant (Triton X-100). It is important that the Triton X-100is completely dissolved in the reagent water prior to adding thepermeant stock standard. This will insure dispersing the test compoundsin the water. In addition, the working standard should be mixedthoroughly each time an aliquot is dispensed. It is advisable totransfer the working standard to crimp-top vials with no headspace tominimize losses due to the large headspace in the volumetric flask usedto prepare the standard.

A working naphtha blend standard is prepared by injecting 800 μL of the“neat” naphtha solvent blend into 100 milliliters of reagent watercontaining 0.2 gram of surfactant (Triton X-100).

An opened stock standard solution should be transferred from the glasssnap-cap vial to a crimp-top vial for short-term storage. The vials maybe stored in an explosion-proof refrigerator or freezer.

2.1 Calibration Standards

Calibration standards are prepared at a minimum of three concentrationlevels by adding volumes of the working standard to a volumetric flaskand diluting to volume with reagent water. One of the standards isprepared at a concentration near, but above, the method detection limit.The other concentrations correspond to the expected range ofconcentrations found in the environment and sample side cells.

3.0 Sample Preparation 3.1 Film Sample Preparation

The permeation test cell as previously referenced, also known as anenvironment flask and sample flask are washed before use in soapy water,thoroughly rinsed with deionized water, and oven-dried. Followingcleaning, each flask is fitted with a rubber septum.

The film test specimen is cut to the inside diameter of the aluminumseal ring using a template. The film test specimen diameter is importantto prevent diffusion losses along the cut edge circumference. The filmsample, aluminum seals, and flasks are assembled as shown in FIG. 3, butthe clamping ring nuts are not tightened.

The test cell is prepared as described by U.S. Pat. No. 5,603,974, aspreviously referenced.

The sample side is injected with 2 μL of water per 300 ml flask volume.Since the sample flasks vary in volume, the water is varied tocorrespond to the volume variations. The 2 μL of water in the 300 mlflask volume is comparable to a 0.25 water activity product at 72° F.Next, 40 μL, the permeation ethanol/aromatic working standard or 40 μLof the naphtha blend working standard prepared according to section 2.2,is injected into the environmental flask. Either of these workingstandards will produce a 60% relative humidity at 72° F. with a permeantconcentration (parts per million-volume/volume) in the 1200 ml volumeflask indicated in Table I. Other humidities or permeant concentrationsmay be employed in the test method by using psychrometric chart todetermine humidity and using the gas loss to calculate permeantconcentration. The time is recorded and the permeation cell placed intoa thermostatically controlled oven. Samples may be staggered toaccommodate GC run time. Three identical permeation devices areprepared. Triplicate analyses are used for QC purposes.

At the end of each time interval, a sample from the group is removedfrom the oven. The environmental flask is analyzed first, using a heatedsix-port sampling valve fitted with a 1 ml loop. The loop is flushedwith a 1 ml volume of the environment-side or sample-side air. The loopis injected onto the capillary column. The GC/FID system is startedmanually following the injection. Up to eight 1 ml sample injections maybe taken from the sample and environment side of a single permeationexperiment.

Sample side and environment side test compound concentrations arecalculated from each compound's calibration curve or response factor(equation 1 or 3). Concentrations are then volume-corrected for eachspecific set of permeation flasks if permeant mass is desired.

4.0 Sample Analysis 4.1 Instrument Parameters

Standards and samples are analyzed by gas chromatography using thefollowing method parameters:

Column: J&W column, DB-5, 30 M, 0.25 mm ID, 1 umdf

Carrier: Hydrogen

Split Vent: 9.4 ml/min

Injection Port Temp: 105° C.

Flame Detector Temp: 200° C.

Oven Temp 1: 75° C.

Program Rate 1: 15° C.

Oven Temp 2: 125° C.

Rate 2: 20° C.

Final Oven Temp: 200° C.

Final Hold Time: 2 Min

The six-port sampling valve temperature is set to 105° C.

4.2 Calibration

A three point calibration is prepared using standards in the range ofthe following test compounds:

Calibration Curve Range Test Compounds ppm (μL) Ethanol  2-20 Toluene0.3-3   p-Xylene 0.2-2   o-Xylene 0.1-1   1,2,4-Trimethyl Benzene0.05-0.5  Naphthalene 0.05-0.5  Naphtha Solvent Blend 4.0-40 

To prepare a calibration standard, add an appropriate volume of theworking standard solution to an aliquot of reagent water in a volumetricflask.

4.2.1 Secondary Dilutions of Working Standard for Calibration Curve

5 to 1 dilution: Place 5 ml of working standard into a 25-ml volumetricflask, stopper, then mix by inverting flask.

2.5 to 1 dilution: Place 10 ml of working standard into a 25-mlvolumetric flask, stopper, then mix by inverting flask.

Analyze each calibration standard and tabulate compound peak arearesponse versus the concentration of the test compound in theenvironment side cell. The results are used to prepare a calibrationcurve for each compound. The naphtha solvent blend is a commercial paintsolvent containing approximately twenty (20) individual aliphatichydrocarbon compounds. The response versus concentration is determinedby totaling the area under each of the twenty individual peaks. Methodof least squares is used to fit a straight line to the calibrationcurve. The slope of each test compound's calibration curve is thencalculated for determining the unknown concentration. The averageresponse factor may be used in place of the calibration curve.

The working calibration curve or response factor must be verified oneach working day by measurement of one or more calibration standards. Ifthe response of any compound varies more than 20%, the test must berepeated using a fresh calibration standard. If the results still do notagree, generate a new calibration curve.

4.3 Analysis of Calibration Curve and Method Detection Level Samples

Recommended chromatographic conditions are summarized above.

Calibrate the system daily as described above.

Check and adjust split vent rate and check rate with soap film flowmeter.

To generate accurate data, samples, calibration standards and methoddetection level samples must be analyzed under identical conditions.

Calibration standards and method detection samples are prepared in theenvironment flask only. This is accomplished by using a ½ inch plasticdisk and aluminum sheet disk the diameter of the environment flange inplace of the sample flask. A single sealing ring is placed onto theenvironmental glass flange followed by an aluminum sheet, and then theplastic disk.

The environment flask is flushed with dry compressed air to removehumidity in the sample and environment flask. This is done by puncturingthe environment septa with a needle and tubing assembly which permits acontrolled flow of dry air through the flask. The clamp rings areloosely fitted to the flask to eliminate pressure buildup. Afterflushing both flasks for approximately 10 minutes, the needle is removedand the clamp rings tightened, sealing the aluminum sheet against theseal ring.

Next, 40 μl of the permeation ethanol/aromatic working standard orsecondary dilutions of the working standard is injected into theenvironment flask. Alternatively, 40 μL of the naphtha solvent blend orsecondary dilutions of the working standard is injected into theenvironmental flask. The time is recorded and the flask is placed into athermostatically controlled oven.

At the end of 30 minutes, the environment flask is removed from theoven. The environmental flask is analyzed using a heated six-portsampling valve fitted with a 1 ml loop. The loop is flushed with a 1 mlvolume of the environment-side or sample-side air. The loop is injectedonto the capillary column. The GC/FID system is started manuallyfollowing the injection.

4.4 Calculation of Results 4.4.1 Test Compound Response Factor

Sample-side and environment-side test compound concentrations arecalculated for each compound's calibration curve slope or responsefactor (RF). Concentrations are then volume-corrected for each specificset of permeation cells if permeant mass is desired. $\begin{matrix}{{{Concentration}\quad {of}\quad {Compound}\quad {in}\quad {ppm}} = \frac{{Peak}\quad {Area}}{{Calibration}\quad {Curve}\quad {Slope}}} & (1) \\{{{Compound}\quad {Specific}\quad {RF}} = \frac{{Concentration}\quad {of}\quad {Compound}\quad {in}\quad {ppm}}{{Peak}\quad {Area}}} & (2)\end{matrix}$

 Concentration of Compound in ppm = Peak Area X RF  (3)

The cumulative penetrant mass is plotted as a function of time on boththe upstream (environment) and downstream (sample) side of the film. Thediffusion rate and transmission rate of the permeant area calculatedfrom the transmission curve data.

4.4.2 Transmission Rate

When a permeant does not interact with the polymer, the permeabilitycoefficient, P, is usually characteristic for the permeant-polymersystem. This is the case with the permeation of many gases, such ashydrogen, nitrogen, oxygen, and carbon dioxide, through many polymers.If a permeant interacts with polymer molecules, as is the case with thepermeant test compounds used in this method, P is no longer constant andmay depend on the pressure, film thickness, and other conditions. Insuch cases, a single value of P does not represent the characteristicpermeability of the polymer membrane and it is necessary to know thedependency of P on all possible variables in order to obtain thecomplete profile of the permeability of the polymer. In these cases, thetransmission rate, Q, is often used for practical purposes, when thesaturated vapor pressure of the permeant at a specified temperature isapplied across the film. Permeability of films to water and organiccompounds is often expressed this way. $\begin{matrix}{P = \frac{\left( {{Amount}\quad {of}\quad {Permeant}} \right)\quad \left( {{Film}\quad {Thickness}} \right)}{\left. {({Area})\quad ({Time})\quad {Pressure}\text{-}{drop}\quad {Across}\quad {the}\quad {Film}} \right)}} & (4) \\{Q = \frac{\left( {{Amount}\quad {of}\quad {Permeant}} \right)\quad \left( {{Film}\quad {Thickness}} \right)}{({Area})\quad ({Time})}} & (5)\end{matrix}$

In this application, Q is represented in units of$\frac{{gm}\text{-}0.001\quad {inches}}{100\quad {in}^{2}\text{-}{day}}.$

One of the major variables in determining the permeation coefficient isthe pressure drop across the film. Since the transmission rate Qincludes neither pressure nor concentration of the permeant in itsdimensions, it is necessary to know either vapor pressure or theconcentration of permeant under the conditions of the measurement inorder to correlate Q to P.

The pressure-drop across the film from environment side to sample sideis principally due to water vapor pressure. The water concentration orhumidity does not remain constant and is not measured during the timeintervals the organic compounds are analyzed, and therefore the pressureacross the membrane is not determined.

The above examples of thermoplastic films containing a variety ofcompatible cyclodextrin derivatives shows that the invention can beembodied in a variety of different thermoplastic films. Further, avariety of different compatible derivatized cyclodextrin materials canbe used in the invention. Lastly, the films can be manufactured using avariety of film manufacturing techniques including extrusion and aqueousdispersion coating to produce useful barriers.

Migration from Food and Beverage Packaging Materials

The migration of trace amounts of reaction and degradation byproducts,additives, oligomers and monomers from food and beverage packaging canaffect consumer acceptance, product quality and regulatory approval ofcandidate packaging materials. Tests were conducted to measure thetransfer of these substances from packaging films with and withoutacetylated cyclodextrin using a method from The Center for Food Safetyand applied Nutrition of the U.S. Food and Drug Administration (FDA).The method simulates the expected migration of these substances in apackaging film to a particular food type, but the packaging testmaterial is subjected to accelerated testing which simulates migrationoccurring to real food under normal conditions of packaging and storage.

We produced six experimental high density polyethylene (HDPE) testfilms. One of the films contained 0.5% (wt/wt) acetylated αcyclodextrin, two contained a acetylated β cyclodextrin at 0.5% and 1.0%loading levels, and two contained a mixture of acetylated α and βcyclodextrin at 0.5% and 1.0% loading levels. The sixth film was acontrol made from the same batch of HDPE (DOW 640) and additives(Dynamar FX-9613 processing additive; Irgafos 168 and Irganox 1076antioxidants) but without cyclodextrin. The films were fabricated byblown film extrusion and had a normal thickness of 2 mil.

Migration testing was conducted according to FDA guidelines forfood-simulating liquids. The migration cells were for single sidedflexible film and conform to ASTM F34-92. The food simulating liquid was8% ethanol in deionized water and test temperature 40° C.

The food-simulating liquid (FSL) was withdrawn from the extraction cellafter seven days. The FSL was reduced in volume, exchanged withmethylene chloride and then analyzed by gas chromatography using flameionization detection. The gas chromatograms of the six test film FSLextracts are provided in the attached figures. The peaks indicated inthe chromatograms are migrants that diffused from the HDPE film into theFSL.

The reduction in the migrant amount was determined quantitatively bycomparison of the gas chromatographic total peak areas from 4 minutes to30 minutes. Film samples containing acetylated cyclodextrin werecompared to the control film made from the same HDPE resin and additivesbut without cyclodextrin. The percent reduction of extractable migrantsin the 8% ethanol FSL was determined using the following equation:${\% \quad {Reduction}\quad {in}\quad {Extractables}} = \frac{- \left( {{{Control}\quad {Film}\quad {Total}\quad {Peak}\quad {Area}} - \quad {{Sample}\quad {Film}\quad {Total}\quad {Peak}\quad {Area}}} \right)}{{Control}\quad {Film}\quad {Total}\quad {Peak}\quad {Area}}$

We were interested in the extent of migration of trace amounts ofreaction and degradation byproducts, additives and oligomers in filmswhose resin contained acetylated cyclodextrin by comparing their gaschromatographic results with film whose resin did not contain acetylatedcyclodextrin. These results are provided in Table 1.

GC/FID Analysis Results of Single Sided HDPE Film Extractions* 8%Ethanol in Water Extraction Seven Days at 40° C. Extractable OrganicReduction in Cyclodextrin Loading Components Expressed ExtractableComponents Sample Film Level in HDPE Film as Total GC Peak Expressed asa % of Identification % by wt. Areas Control Film Control HDPE Film NA20,720 NA Acetylated α Cyclodextrin 0.5% 9,592 54% Acetylated βCyclodextrin 0.5% 869 96% Acetylated β Cyclodextrin 1.0% 1,651 92%Acetylated α and 0.25% ea. 3,473 83% Acetylated β CyclodextrinAcetylated α and 0.5% ea. 16,125 22% Acetylated β Cyclodextrin *ASTMDesignation: F34-92 for Standard Practice for Construction of Test Cellfor Liquid Extraction of Flexible Barrier Materials

Simulated Volatiles Migration from Food and Beverage Packaging Pellets

Food that comes into direct contact with polymeric packaging materialsmay result in the transfer or migration of volatiles into the storedfood product. Though the package materials are approved for direct foodcontact, they can impart flavors to the food. Volatiles can becomeincorporated into the pellets during the manufacturing process. Whenthese pellets are converted to film, the flavor of the film can beaffected by the residual volatiles.

We compounded four experimental polypropylene (Montel 8623) pellets.Three of the compounded pellets contained acetylated α cyclodextrin,acetylated β cyclodextrin, and a 50%/50% mixture of acetylated α and βcyclodextrin each at a loading level of 0.75% (wt/wt). The fourth was acontrol pellet made from the same batch of polypropylene resin andadditives (Dynamar FX-9613 processing additive; Irgafos 168 and Irganox1076 antioxidants) but without cyclodextrin.

The method consists of three separate steps; the first two are carriedout simultaneously while the third, an instrumental technique forseparating and detecting volatile organic compounds, is conducted afterone and two. In the first step, an inert pure, dry gas is used to stripvolatiles from the sample. During the gas stripping step, the sample isheated at 120° C. The sample is spiked with a surrogate (benzene-d6)immediately prior to the analysis. Benzene-d6 serves as an internal ZCsurrogate to correct each set of test data for recovery. The second stepconcentrates the volatiles removed from the sample by freezing thecompounds from the stripping gas in a headspace vial immersed in aliquid nitrogen trap. At the end of the gas-stripping step, an internalstandard (toluene-d8) is injected directly into the headspace vial andthe vial is capped immediately. Method and system blanks areinterspersed with samples and treated in the same manner as samples tomonitor contamination. The concentrated organic components are thenseparated, identified and quantitated by heated headspace highresolution gas chromatography-mass spectrometry (HRGC/MS). The resultsof the residual volatile analysis are presented in Table 1. The GC/MStotal ion chromatograms are provided in the Figures.

Headspace GC/MS Analysis Results of Extruded Polypropylene PelletsPellets Heated to 12° C. for 45 Minutes Reduction in Mobile VolatileOrganic Mobile Volatile Components in Cyclodextrin Loading OrganicComponents Acetylated CD Pellets Sample Pellet Level in PP PelletsExpressed as Total Expressed as a % of Identification % by Wt. GC PeakAreas Control Pellets Control Pellets NA 16,294,162 NA Acetylated αCyclodextrin 0.75% 2,365,120 85% Pellets Acetylated α Cyclodextrin 0.75%4,109,950 75% Pellets (Duplicate) Acetylated β Cyclodextrin 0.75%8,977,360 45% Pellets Acetylated α and 0.375% ea. 2,938,261 82%Acetylated β Cyclodextrin Pellets Acetylated α and 0.375% ea. 3,896,85476% Acetylated β Cyclodextrin Pellets (Duplicate)

The above explanation of the nature of the cyclodextrin derivatives, thethermoplastic materials, coatings and containers, manufacturing detailsregarding the containers, provides a basis for understanding thetechnology involving incorporating the cyclodextrin material in PETcontainers for barrier and trapping purposes. However, since manyembodiments of the invention can be made without the party from thespirit and scope of the invention, the invention resides in the claimshereinafter appended.

What is claimed is:
 1. A thermoplastic preform suitable for blow moldinginto a beverage container having improved barrier properties andresistance to the extraction of soluble materials from the containermaterial, the preform comprising a major proportion of a thermoplasticpolymer and uniformly dispersed in the polymer, an effective barrier andbeverage extractable compound absorbing amount of a modifiedcyclodextrin material, substantially free of an inclusion complexcompound, said cyclodextrin having pendant moieties or substituents thatrender the cyclodextrin material compatible with thermoplastic polymer.2. The preform of claim 1 comprising a polyester condensationpolymerization reaction product of a diol and an aromatic diacidcompound.
 3. The preform of claim 1 wherein the aromatic diacid compoundcomprises terephthalic acid, dimethyl terephthalate, 2,6-naphthalenedicarboxylic acid, dimethyl-2,6-naphthalene dicarboxylate.
 4. Thepreform of claim 1 wherein the diol comprises ethylene glycol or1,4-butane diol.
 5. The preform of claim 1 wherein the cyclodextrinmaterial is present in an amount of about 0.1 to 10 wt % based on thebulk material.
 6. The preform of claim 1 wherein the polyester comprisespolyethylene-co-terephthalate) or poly(ethylene-co-2,6-naphthalenedicarboxylate).
 7. The preform of claim 1 wherein the polymer ispolyethylene or poly(acrylonitrile).
 8. The preform of claim 1 whereinthe modified cyclodextrin material comprises an acyl cyclodextrin. 9.The preform of claim 1 wherein the modified cyclodextrin materialcomprises a silicone modified cyclodextrin.